Why does my computer at work tell me that a 2wd pump fits 73-79 and my 77 4wd pump only fits 77-79 4wd, 400 engine only? I know the car pump wont fit, ask me how I know, and an Oldsmobile pump wont fit because the pump itself is clocked different in the resevoir and the chev bracket wont fit.

Any help is appreciated.

It probably has something to do with the fact that the 2wd boxes operate laterally and the 4wd boxes operate longitudinally (pretty sure I spelled that wrong) One must need more fluid than the other or something of the sort.

its a possibility, I used the 4wd pump (stock) when I put the 2wd box on my 78 chev for the crossover steering, and even pushing 44's, it has no problems, and I only run severe duty power steering fluid, never any atf at all.

The steering gear makes no difference. The Pitman arm is indexed differently, that's all, and has no effect on the pump.

I don't know why you're having trouble. I have interchanged pumps before... no trouble.

I don't know why you're having trouble. I have interchanged pumps before... no trouble.

The bracket off the car had the wrong style of adjusting ear on the side, and my truck bracket wont fit on the car pump, it hits the top of the resevoir and wont bolt on because of it. It is also clocked different than the truck one, I might have to just buy a new one, 50 bucks new (no resevoir) or 65 used. I have all the tools, I think a new one will have to work, I need my junk back on the road by friday, but money is tight.

ahh I skimmed.

If that's all, yeah, you're SOL. Any decent yards nearby????

Do you have the truck one w/the remote reservoir or just the normal ham-can deal??

Somewhere in those years they also went from a flared fitting to an O ring fitting

on the back of the pump, the fitting is easily changed from flare to the o-ring style, just takes a 15/16" wrench IIRC. everything else should be pretty much the same, although there were a couple different pumps.