Thanks for the info! the 153 flywhel is smaller in D, when you look in the starter hole with the 153, you only see the teeth, with the 168 you see the flywheel also, All those drives look bigger like the 153 uses the vair might work-- I'll have to look!

My guess is that when Chev/GMC went to the bigger engines, they went to a bigger flywheel AND clutch for the potential Hp, of courswe you can get a 9 1/2" or 10" clutch that will handle 300 HP but the standard one might not!

I have a Schaffer allow wheel that I want to use AND the stocker on the engine IS the 168 probably because a clutch will experience heavy use! I have a 54 dump with probably a 260 I'll look to verify it has a stomper.