I actually used the pressure plate from the SM-420 and the clutch disc from the truck I pulled the tranny from. It was the same diamter as the one on the SM-420!

I also used a hydraulic throw out bearing and clutch master cylinder, but that was 'cause the clutch arm was hitting the power brake booster.

'51 Chevy 1/2 ton w/'62 261, HEI, offy, fentons, dual carter/webbers, t-5 & 12 bolt posi