I just installed a Gen V 454 in a 66 c10 with manual clutch I used the original 66 bellhousing & new stock rear motor mounts. Worked very well I’m using a m20 4 spd with a 66 11 inch clutch. It all fits like it came from the factory that way. FYI, if your 61 came with a 235 6 cyl, you’ll need to get a v8 bell housing. If you’ve got a later 230 or 250 6, then tha by will fit your 302

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