My 66 C10 came with a 230 L6 & 3 spd on the column. I installed a Gen V 454 w/ Muncie M20 4 spd using the 66 bellhousing. I just bought the stock replacement 11" clutch assembly for the 66 c10 from AutoZone & a stock replacement Gen V flywheel. In your case just order the 65 flywheel. The clutch kit came with the crank bushing (or bearing in my case) & the throwout bearing. I've put around100 miles on it so far & t's all working out very well. As an FYI, 6's & V8's used the same flywheel in 65.

1966 C-10 Short Stepside
HiPo
Step-by-step ~ and on-going resto build
in the Project Journals