Originally green sbc 350/TH350. Then Olds 307/TH250C and then Olds 350/TH250C. Full length A body headers and 2.25" duals. It had the 12 bolt with 2.78 open then Detroit's copy of the lock right after breaking the cross pin and spider gears getting stuck.
Alright, here's a current pic of the 80 K10. This was a $600 pile I bought back in 2015 to be a father/son project with my then 15 year old. It quickly morphed into a father doing it by myself project. It's now made up of many different squarebodies. Cab is an 84 I found on Craigslist for free from another stalled father/son project, it needed cab corner work, but came with new outers, I bought new inner corners and outer rockers. Poly cab mounts, new chinesium fenders, blah blah blah. 350, 4 speed, NP205. New 4" Rough Country lift, new springs on all corners and was more like 6". Home built front bumper waiting for a deal on a winch.
Piece of cake! Used the 80 linkage which required the holes drilled out to the early pattern, the holes for the longer 81 up linkage are in different spots. Measured it all off the old cab. I also filled in the spots where the 81 up hinges pass through the cowl and welded in nuts to bolt the early rear hood adjuster bolts in. The plastic screen on the 80 cowl even clips in place!