[jonzcustomshop]

c/10-c 80 will work. 60-61 will be called viking or spartan, and have the # series on the fender (60)or grille(61)
the lcf cab (snub nose c/50-80) will not work
there are some minor fitment issues-
front frame location holes are either inboard or outboard depending on the truck- a simple fix by drilling a hole .
c 50-c80 have different lower inner fender mounts, 60-64 they are bolt on and a easy change out, 65-66 are one piece, and have to be trimmed out of the way, and use an earlier c10/40 bolt on mount
the transmission tunnel has to be changed out with the one from a c/10-40 (I did come across 1 64 c/80 that had an allison 5 speed, it had a low hump tunnel instead of the regular flat big truck tunnel.)

other minor things: save your c/10-40 column drop, some of the later big trucks still used the dual master cylinder/hydraulic clutch, like the 60-62 c/10-40,there is a support brace across the belhousing area on the c/50-80 that needs to be removed (unbolted).
here is a pic of the 2 cabs that won't work: