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This custom flex plate kit is designed to adapt the Gen III / LS series to the GM TH400 transmissions. The kit includes a flexplate, 11mm flex plate bolts, crank spacer.

 

The new style Gen III / LS series engines (4.8, 5.3, 5.7 LS1, 6.0, 6.2) all have the same crank stick out which is .400” closer to the block than the old 350 V8. The Gen III / LS series crank bolt pattern is different than any other GM crank as to the bolt pattern on the flex plate. Only Gen III / LS series flexplates fit these engines!!!

 

Since a Gen III / LS series flexplate only fits a Gen III / LS series and the engine crank is recessed .400”. There are a few unique things about the torque converters that bolt to the flexplate. The spacing of the flexplate from the back of the block is the same as early GM blocks. The flexplate is dished out .400” to compensate for the crank. The differences come into play as to the bolt pattern of the torque converter to the flexplate and the snout length of the torque converter.

 

How do we adapt TH400 to a Gen III / LS series engine? We offer a custom flexplate to fit a TH400 and a crank spacer that  compensates for the shorter engine crank.

Note: This Advance Adapter kit does not work with a 6.0 engine with cast-iron cylinder heads.

 

The photo show kit PN717514 collector rings and gaskets which are sold separately.

Instructions / Downloads
712500A4.pdf