I'm a little confused. Was the "Apache" name also assigned to GMCs? I thought that was a Chevy thing. If it is a Chevy, here is some of what I know. Available motors were the 235 inline 6 and the 283 V-8. Trannies are 3onthetree, 4onthefloor, or automatic. Mine came with a posi-rear and a heavy-duty clutch that was optional with the 4spd.
There are a bunch of vendors(American Classics, Jim Carter, LMC, etc...) that sell the literature you want. A shop manual is a must have. The owners manuals are good to have and available as well. I even have an accessories manual.
http://rides.webshots.com/photo/2073377370071636143DJNLon They also have a factory assembly manual, but you just about have to be an engineer to understand it.