early A-bodies 1966 and back used a 9-1/2" clutch with a 122 tooth flywheel
67 and later used the 10-1/2" clutch with a 130 tooth flywheel
many people upgrade to the later, bigger set up as the early smaller one kind of sucked
to do that you also need to change to a later 67 and up bellhousing and use an aftermarket conversion Z-bar http://www.brewersperformance.com/proddetail.asp?prod=TS636