I know I should know this, but is this flywheel a GM piece or aftermarket? I can't find any markings or numbers on it at all, and the reason I ask is in the third photo - for some reason the flywheel to crank bolts have bern rather crudely machined - is there some kind of interference going on between the clutch disc and the heads of the bolts due to lack of clearance from an aftermarket design? Thanks!!

 

Looks like an exact match to the one I have from 70 442 w-30?

 

Looks like whatever hit on those bolts was a time ago, or they would still be shiney? If this car was a drag car it probably had a lot of clutches replaced and maybe those marks are from a mistake years ago.

 

It's a GM flywheel.

Check the minimum thickness, as if it has been machined, the bolts look like that.