1997-2008 GM LS1, LS2, LS6 Steel Flexplate TH350/700R4/4L60

• Fits all standard 6-bolt crankshaft 1997-2008 Gen III and Gen IV LS engines
• Not for use with early Gen III LS 6.0L (1999-2000) due to extended crankshaft flange
• Allows direct bolt-on fitment of previous generation automatic transmissions
• Supports non-LS 4L60 as well as popular older 3- and 4-speed automatics
• No modifications required to LS engine block or crankshaft for transmission fitment
• New LS flexplate features dual GM torque converter patterns of 10.75” and 11.10”
• Flexplate is gold zinc plated and 4mm thick with double welded 168-tooth ring gear
• Not compatible with 8-bolt crankshaft Gen IV LS, Gen V LT, and some LSX engines

Make Your LS Transmission Swap Easier with Our Conversion Flexplate

There are many reasons why GM’s V8 engine family is one of the most swapped engines in hot rod history. GM’s engineers wisely kept the same bolt patterns for many engine components, allowing most swaps to be a simple bolt-on affair with minor custom fitting or an adapter of some sort. One such bolt pattern is the bellhousing configuration. The Gen 1 small block V8 bellhousing bolt pattern is commonly referred to as the “Chevrolet V8 pattern” and was used on both small and big-block GM V8 engines along with several other GM applications over many years, including the Iron Duke 4-cylinder, Duramax V8, and GM’s Vortec 4300 V6 engines. Additionally, this pattern was utilized with the Gen III small block design (commonly known as the LS V8) with some minor tweaks. What this means is that when you’re considering an LS swap in your project you have a wide choice of early GM transmissions to choose from.

You will find that most non-LS GM automatic transmissions, including the TH350, 700-R4, or even the venerable Powerglide will bolt directly to the Gen III and early Gen IV engine block with no modifications, though it does so with one less bellhousing bolt. The swap issue lies inside the bellhousing with the flexplate and torque converter relationship and how they attach. To address this spacing issue in the most cost effective way possible we offer a custom LS flexplate with the LS 6-bolt crankshaft pattern and 168 tooth count. The center section is 4mm thick, which is .035-inch thicker than a stock LS flexplate and features a forged 1-piece ring gear that is double welded (both sides of the flexplate). The LS flexplate is drilled for both early SBC torque converter bolt patterns (10.75" which fits Powerglide, TH350, 200-4R, 700-R4, 4L60) and later LS converter pattern (11.06” 4L60E with LS engine). We even made sure our LS flexplate allows the use of the stock LS starter, which is one less swap part to worry about/buy.

To properly support the SBC-style torque converter found in these earlier transmissions, a machined adapter sleeve will be needed. This LS flexplate spacer engages the torque converter hub and the LS crankshaft, maintaining concentric support of the torque converter as it is mounted to the flexplate. We also offer the correct LS flexplate bolts and the torque converter bolts to mount your new LS flexplate and attach your torque converter. Then you will have everything you need (except bellhousing bolts if needed) to easily adapt an early GM three speed or four speed automatics to your LS engine.

A Must Have Time Saving Part for Your LS-Powered Build

It is a well-known fact that far too often “bolt on” parts don’t just bolt right on and can cause all manner of project car stress. However, if you’re fitting a small block or big block Chevy classic transmission, such as the popular Turbo 350 or the 700R4, to a 6-bolt Gen III LS V8 this flexplate is the perfect solution. Fitment applications include such common LS engines as the 1997-2007 LS1, LS3, LS6, and LS7; 2005-2009 LS2; and Vortec truck engines including the 4.8/5.3/6.0 under RPO codes L33, L59, LM4, LM7, LQ4, LQ9, and LR4. Besides the popular TH350 3-speed automatic and classic Powerglide 2-speed, this flexplate will also work with GM’s non-LS 4-speed overdrive transmissions like the 200-4R, 700-R4, and 4L60 thanks to the dual converter bolt patterns drilled into it.

Stamped from 4mm thick steel plate, laser cut torque converter and crankshaft mounting bolt patterns and given a 168-tooth forged steel ring gear that is welded on both sides of the flexplate, you know this flexplate will last the life of your project! Given a gold zinc plating for corrosion inhibition, this flexplate is ready to bolt on right out of the box and solve your LS swap transmission fitment issues. Designed for a precision fit on all 6-bolt internally balanced LS crankshafts, this flexplate interfaces with stock and aftermarket LS starter motors for quick and efficient engine starting without any gear grinding, binding, or spacing issues.

Note that this flexplate does not support the TH400 3-speed automatic natively due to its larger 11.50” converter bolt pattern, if you wish to use a TH400 behind your LS you can simply swap your TH400 converter for a TH350 converter and everything will bolt right up then as a pseudo LS to TH400 adapter kit. The modern 4L80E uses the same 11.50” bolt pattern, but is not compatible with this flexplate, nor will this flexplate fit extended length crankshafts, such as early 6.0L applications, or 8-bolt crank Gen IV LS engines such as the LSA. If you’re looking to run a classic GM automatic behind your LS for transmission tunnel fitment purposes, or perhaps you have a custom built transmission from a past project car you wish to use, this LS to TH350 adapter flexplate will help you get it done quickly and easily. Be sure to read our LS flexplate guide in The Toolbox to explore other flexplate options that may be viable for your build.