I am looking for some info for my 77K5. It has a 396 matted to a sm465. My clutch is just about to go and I am not for sure what size flywheel I have. Is there any way to find out with out taking the tranny down? I was also wondering if it was internal or external balanced. I am planning on buying a centerforce dual friction clutch. Does anybody have any feed back on that decision. Let the heavy chevys ride on.