I have a 1966 c-10 short bed fleet restored to mostly original condtion with a few improvements like disc brakes. Question it has "three on the tree" transmission. What would be a common four or five speed manual transmission (floor shift)that would slide in and take the place of the old three speed trany.
If you want a no-mod drop in find a saginaw 4 speed. It should hold up find behind the 292. A muncie MIGHT fit also, I'm not sure. And MAYBE a short-tailshaft 350. But you'd have to change the driveshaft yoke at a minimum. Any other trannies (th400, 700R4, etc.) would require driveshaft shortening. Not too big a deal and not too expensive.
Hey thats the same thing Im gonna do to my 65 longbed. It very wise to keep that strong 292, my 292 sounds just like new. But I dont even know what type of tranny Ill put in her. Most likely four speed but dont know which kind. Good luck on yours and if you find one that is real good tell me about it.