If your avatar pic is your truck, then I would guess it is a 76-77 Ford... cant tell if 1/2 or 3/4 ton... best bet is a 205, but it could be a 203... Do you just have 4lo, neutral, 2wd, and 4hi (if so, 205) or do you have **** like HI LOC, HI, N, LO, LO LOC (then it is a 203)
Or you could just climb under it, find the shiny little red / chrome tag on the case, scrape the grease off of it, and read what it says...:flipoff: