Centerforce P/N 704142 Steel Billet Flywheel Conversion for GM LS Gen III and IV V-8 Engines GM LS/Vortec engine platforms have a crankshaft mounting flange for the flywheel that is about 3/8" closer to the back of the engine than earlier generation (pre-1997) GM small blocks. When performing an LS engine swap in conjunction with an early (pre-LS) manual transmission, this difference causes several issues. Centerforce now offers a 168-tooth Steel Billet Conversion Flywheel Part Number 704142 to facilitate these swaps. This flywheel mates to 1997 and later GM LS engines while offering the proper flywheel thickness (+0.400") to use in conjunction with the mechanical clutch linkage on many common early model transmissions. These include: Muncie SM465, GM SM420, New Venture NV3550, Chrysler NSG370 , GM Muncie, Borge Warner T-10, Richmond 4 and 5-speeds Centerforce flywheel #704142 comes pre-drilled with pressure plate bolt patterns for early GM 11" and 12" (3/8" bolts) as well as late-model metric GM 11" and 12" patterns with dowel pins. See Centerforce Product listings at www.centerforce.com or contact our tech line at 800-932-5882 for more information regarding pressure plate and disc combinations for your LS swap application. Note: Centerforce flywheel #704142 is not compatible with the GM 4.3L V-6 or Atlas series engines.