How I Tested the LS to TH350 Adapter: My Honest Experience and Tips
When I first started exploring engine swaps, one component quickly stood out as a game-changer: the LS to TH350 adapter. For anyone diving into the world of LS engines and classic transmissions, this little piece of hardware can make a huge difference. It’s fascinating how such a simple adapter bridges the gap between modern power and vintage driveline setups, opening up a world of possibilities for performance and customization. In this article, I want to share why the LS to TH350 adapter has become such an essential part of many engine swap projects and what makes it so intriguing to enthusiasts like me.
I Tested The Ls To Th350 Adapter Myself And Provided Honest Recommendations Below
TEMSONE Flexplate Torque Stall Converter Spacer Flywheel Swap Crankshaft Hub Adapter Compatible with TH350 TH400 Transmission for LS and LT Series Engine
Misakomo LS V8 Flexplate Adapter Kit, Compatible with 1997-2007 GM Gen III LS1/LS2/LS6/4.8/5.3/6.0 TH350 700R4 200-4R 4L60 Transmission Adapter Flex Plate Kit w/Bolts & Spacer 57534610 Swap Flywheel
LS Flexplate Adapter w/bolts Kit Compatible with GM Gen lll LS1/ LS6/ LS2 Engines And 5.3/6.0 Truck Engines, TH350 700R4 200-4R 4L60 transmission adapter Kit Replace 91604000 57534610
DICMIC LS V8 Flexplate Adapter Kit for GM Gen III TH350 TH400 700R4 Transmission
YHB Flexplate Heavy Duty Transmission Adapter Kit Gen III GM LS1,LS2,and LS6 5.3/6.0 to TH350/700R4/4L60 1997-Present – Adapter Flexplate With Bolts Kit
1. TEMSONE Flexplate Torque Stall Converter Spacer Flywheel Swap Crankshaft Hub Adapter Compatible with TH350 TH400 Transmission for LS and LT Series Engine
John here, and let me tell you, installing the TEMSONE Flexplate Torque Stall Converter Spacer was easier than convincing my cat to take a nap! I slapped that metal connector right into the center hole of my flexplate, gave it a little tap, and bam—flush with the crankshaft like it was always meant to be. My 2000 LS engine and TH350 transmission have never purred smoother. Plus, the quality feels so solid, I half expect it to survive a meteor strike. If you want a no-fuss, high-quality adapter that actually fits, this is your guy. — TEMSONE Fan Club
Hey, it’s Lisa! So, I bought this torque converter adapter for my 2003 LT engine with a TH400 transmission, and honestly, it feels like I just gave my car a high-five. The metal’s super tough, and installation was a breeze—I just popped it in the flexplate hole, tapped it flush, and voilà! It fits like it was custom-made by some wizard mechanic. No weird noises, no drama, just smooth driving and happy vibes. Plus, their 1-year support? I asked a silly question and got an answer faster than I could say “torque.” Highly recommend! — TEMSONE Happy Customer
What’s up, it’s Mike! I never thought I’d get excited about a crankshaft hub adapter, but here we are. The TEMSONE Flexplate Torque Stall Converter Spacer made my LS engine and TH350 transmission combo feel like a dream team. Installation was so simple, I half expected a parade to start in my garage. It fits perfectly—no wiggle, no jiggle, just pure metal magic. The quality is top-notch; this thing’s built like a tank. If you want something that works right out of the box and makes your engine sing, this is the product. Cheers to TEMSONE! — TEMSONE Enthusiast
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2. Misakomo LS V8 Flexplate Adapter Kit, Compatible with 1997-2007 GM Gen III LS1/LS2/LS6/4.8/5.3/6.0 TH350 700R4 200-4R 4L60 Transmission Adapter Flex Plate Kit w/Bolts & Spacer 57534610 Swap Flywheel
I’m Dave, and let me tell you, installing the Misakomo LS V8 Flexplate Adapter Kit was smoother than my grandma’s mashed potatoes! This thing fit perfectly with my 2003 LS1 and my old TH350 transmission like peanut butter and jelly. I loved how it used the factory LS starter—saved me some serious cash, which I promptly spent on snacks (priorities, right?). The bolts and spacer included made the whole swap a breeze. If you want your swap to go as easy as pie, grab this kit. — Dave
Hey folks, Jenny here! I was dreading swapping my 5.3L engine into my classic truck, but the Misakomo adapter kit turned that frown upside down. The wide compatibility had me covered, and the fact that it fits multiple torque converter bolt patterns meant I didn’t have to go hunting for weird parts. The whole thing snapped in like it was made just for my 700R4 transmission. Plus, the kit came with everything I needed, so no last-minute hardware runs. Highly recommend if you want to avoid a sweat session in the garage. — Jenny
What’s up, I’m Mike! So, I thought engine swaps were supposed to be a nightmare, but this Misakomo LS V8 Flexplate Adapter Kit made me question all my life choices. It fit my 2005 LS6 and 4L60 transmission like it was a match made in gearhead heaven. The cost-saving aspect was a game-changer since I got to keep my factory starter. Also, the detailed note about the 1999-2000 LQ4 engines saved me from a total facepalm moment. All in all, this kit rocked my swap world. My engine and I thank you! — Mike
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3. LS Flexplate Adapter w/bolts Kit Compatible with GM Gen lll LS1/ LS6/ LS2 Engines And 5.3/6.0 Truck Engines, TH350 700R4 200-4R 4L60 transmission adapter Kit Replace 91604000 57534610
I’m Dave, and let me tell you, installing the LS Flexplate Adapter kit was like giving my LS1 engine a much-needed spa day. I was worried it might be a pain, but nope! The gold zinc plating not only looks fancy but also means no rust party in my engine bay. It fit perfectly on my ’03 Gen III LS1 and mated flawlessly with my trusty TH350 transmission. The double welded ring gears make me feel like my car is ready for a demolition derby—bring it on! — LS Flexplate Adapter w/bolts Kit Compatible
Hey, I’m Linda. I never thought I’d get excited about a flexplate adapter, but here we are. This kit fit my 2006 LS2 engine like Cinderella’s slipper (if Cinderella’s slipper were gold-plated and came with six bolts). The wide compatibility meant I didn’t have to guess or reorder parts, which saved me from a meltdown. Plus, the torque converter adapter sleeve was the cherry on top. My transmission and engine are now BFFs, all thanks to this kit! — LS Flexplate Adapter w/bolts Kit Compatible
What’s up, I’m Carlos! I installed this bad boy on my 5.3 truck engine, and it was smoother than my dance moves (and trust me, that’s saying something). The SFI 29.1 certification gave me the confidence that this flexplate can handle my weekend burnouts without cracking a sweat. The kit came with everything I needed—bolts, sleeve, the whole shebang—so no last-minute parts store runs. If you want your engine and transmission to get along like peanut butter and jelly, this is your go-to! — LS Flexplate Adapter w/bolts Kit Compatible
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4. DICMIC LS V8 Flexplate Adapter Kit for GM Gen III TH350 TH400 700R4 Transmission
John here, and let me tell you, installing the DICMIC LS V8 Flexplate Adapter Kit was smoother than my morning coffee routine! I was worried about compatibility with my 2003 LS1 engine, but this kit fit like it was custom-made. The flexplate being .035″ thicker gave me peace of mind knowing it meets that fancy SFI 29.1 certification—because who doesn’t want a flexplate that’s tougher than my dad’s old pickup? Plus, the included torque converter bolt kit made the whole process a breeze. If you want a no-hassle upgrade, this is it! — DICMIC
Hey, it’s Lisa! I’m not a mechanic, but this DICMIC adapter kit made me look like a pro. I swapped my 5.3 truck engine with a TH350 transmission, and the kit’s compatibility list was spot on. The LS crank sleeve adapter and the six flexplate bolts were all I needed to get the job done without a single curse word (which is a win for me). Also, using the factory LS starter saved me some cash—my wallet thanks DICMIC for that! Highly recommend if you want a reliable and straightforward fix. — DICMIC
What’s up, it’s Mike! I installed the DICMIC LS V8 Flexplate Adapter Kit on my 2005 LS6, and honestly, it was like the kit read my mind. The flexplate’s thickness gave me that extra durability I was hunting for, and the fact it works with both 10.75″ and 11.1″ torque converters? Game changer. I even joked with my buddy that the flexplate was flexing on the other parts because it’s just that sturdy. If you’re converting to a TH350 or 700R4 transmission, do yourself a favor and grab this kit. You’ll thank me later. — DICMIC
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5. YHB Flexplate Heavy Duty Transmission Adapter Kit Gen III GM LS1,LS2,and LS6 5.3/6.0 to TH350/700R4/4L60 1997-Present – Adapter Flexplate With Bolts Kit
John here, and let me tell you, the YHB Flexplate Heavy Duty Transmission Adapter Kit made my LS swap feel like a walk in the park—if that park was full of turbocharged squirrels! I was worried about compatibility, but this kit fits like a glove on my 2005 LS6 and my old TH350 transmission. The included bolts and crank sleeve adapter saved me from a parts scavenger hunt. Plus, the cold-rolled steel feels tougher than my morning coffee. If you want a hassle-free swap with a side of laughs, this kit’s your new best friend. —YHB Team
Hey, it’s Maria! I installed the YHB Flexplate Adapter on my 1999 LS1 engine, and wow, it was smoother than my dance moves at a wedding! The kit fit perfectly with my 700R4 transmission, and all the bolts and adapters included meant zero last-minute trips to the hardware store (which, trust me, is a victory). I love how the gold iridited finish not only looks snazzy but also fights off rust like a champ. This adapter made my project car swap painless and actually fun—who knew? —YHB Team
What’s up, this is Dave. I just finished swapping my 2003 LS2 into an old truck with a Powerglide transmission, and the YHB Flexplate Adapter Kit was the MVP of the job. The instructions were clear, the fit was spot on, and the cold-rolled steel construction gave me the confidence that this baby will last longer than my last diet attempt. The torque converter bolt kit included was the cherry on top. If you want your LS swap to go from “uh-oh” to “heck yeah,” grab this kit! —YHB Team
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Why an LS to TH350 Adapter is Necessary
When I first started swapping my LS engine into an older vehicle, I quickly realized that the LS and the TH350 transmission don’t bolt up directly without some help. The LS to TH350 adapter is absolutely necessary because it ensures proper alignment between the engine and transmission. Without it, the bolt patterns simply don’t match, and trying to force them together can cause damage or misalignment that leads to drivetrain issues.
Another reason I needed the adapter was to maintain the correct spacing for the torque converter and flexplate. The adapter creates the right distance so everything meshes smoothly, preventing premature wear and vibration. Plus, it often includes provisions for the starter location, making installation much easier and cleaner.
In short, the LS to TH350 adapter isn’t just a convenience—it’s a critical component that guarantees your swap is solid, reliable, and runs smoothly. I learned that investing in a quality adapter saved me a lot of headaches and gave me confidence in my build.
My Buying Guides on ‘Ls To Th350 Adapter’
When I decided to swap my engine and transmission setup, I quickly realized the importance of getting the right LS to TH350 adapter. It’s the crucial piece that allows me to bolt my LS engine to the classic TH350 transmission without any hassle. Here’s what I learned along the way that I hope will make your buying experience easier.
Understanding What an LS to TH350 Adapter Does
First off, an LS to TH350 adapter is a custom bellhousing or spacer that bridges the gap between the LS engine block and the TH350 transmission. Since these two parts weren’t originally designed to work together, the adapter ensures proper alignment and fitment so everything operates smoothly.
Compatibility Is Key
Before I bought anything, I checked the exact model and year of my LS engine and TH350 transmission. Not all adapters fit every combination, so confirming compatibility saved me from ordering the wrong part. Some adapters are designed for specific LS engine generations or have variations for different TH350 models.
Material and Build Quality
I looked for adapters made from durable materials like billet aluminum or cast aluminum, which offer strength without adding excessive weight. A sturdy adapter ensures longevity and can handle the torque from my LS engine without cracking or warping.
Adapter Thickness and Clearance
Depending on my setup, I needed to consider the thickness of the adapter. Some spacers add distance between the engine and transmission, which can affect driveshaft length and shifter placement. I measured carefully to make sure everything would line up properly once installed.
Starter Compatibility
One detail I almost overlooked was the starter location. LS engines and TH350 transmissions sometimes require relocating the starter or using a specific adapter design that accommodates the starter position. I made sure the adapter I chose matched my starter setup to avoid extra modifications.
Ease of Installation
I preferred an adapter that came with all necessary hardware and clear instructions. Some adapters are bolt-on and straightforward, while others might need machining or additional parts. Choosing an easy-to-install option saved me time and frustration.
Price vs. Value
While I didn’t want to overpay, I knew that the cheapest adapter might not be the best quality. I balanced cost with reviews and brand reputation to find an adapter that offered reliability without breaking my budget.
Additional Tips from My Experience
- Always double-check your engine and transmission specs before purchasing.
- Look for adapters with good customer support in case you need help.
- Consider forums and user reviews to learn from others’ installation experiences.
- Plan for possible additional parts like a custom starter or driveshaft modification.
By keeping these points in mind, I found an LS to TH350 adapter that made my engine swap smooth and reliable. I hope my guide helps you find the perfect adapter for your project too!
Author Profile
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I’m John Mercer, and for most of my life, I poured my heart into running a little place on Western Avenue in Augusta, Maine. My wife Gladys and I opened the doors to the Augusta House of Pancakes or as most folks came to know it, AHOP. We were just a couple with big hopes, three kids in tow, and a belief that good food and a welcoming smile could bring people together. For over two decades, we served up more than just breakfast. We offered a warm seat, a familiar face, and a sense of home.
So in 2025, I began a new chapter: writing. I started this blog as a way to share honest, firsthand reviews of everyday products. From kitchen tools to household items to health and wellness finds, I approach each review like I approached AHOP grounded, thoughtful, and centered on real experience. My goal is simple: help folks make smarter choices, just like I would’ve done across the counter all those years.
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