"could" be a 60 as I've heard rumor of some 60s being put into a few 3/4 ton Suburbans. Check for king pin knuckles, bigger hubs, larger cover, and of course the "60F" cast into the center section's web. The auto hubs don't mean much as I had a 60 out of an '81 that had them. For the age of the truck, the tranny should either be a TH400 or TH350. Check the pan on the tranny, 350 is square and 400 is not IIRC. The 700r4 did not come out until '82. My guess is that the t-case is a 203 and not a 208, again based on the vintage. the 203 was a full time case and I don't think the 208 came out until the mid 80s.
yeah I"m leaning toward a 60 because like I said it seemed bigger than my 44. I'll take some pictures of it tonight and let you guys take a look. also does anyone know the physical width of the 60 cover because I could get tell from that. I haven't exactly crawled underneath the rig because it in a weed patch. Oh and regarding that transfercase I that was a typo on my part I meant to put 203. Thanks for the help guys.
OH and does anyone know what the width is on full width chevy axles wms to wms on the 14 bolt and front axle.