Conventional TH350 and TH400 converters are interchangeable. Some TH350s built since 1979 have used lockup torque converters. Due to differences in the stator-shaft spline count, conventional TH350 ...
Horsepower has a way of finding hiding places throughout the drivetrain. You might be sacrificing a few horsepower here and there due to normal parasitic loss or you might be dealing with a much more ...
For straight line guys, spending hundreds of dollars on something that doesn't give you any extra horsepower doesn't exactly seem like a good deal. Even a federal bean counter could figure that one ...