I have a wide track D44 on my j10, it measures out to like 64.5" WMS to WMS, how much width would I add If I went to 3/4 ton 8 lug outers, and what version do I use??? I need calipers, rotors, spindles, hubs,?? what else, and is there differences inFord to Chevy stuff, chances are I wont be finding a j20, also intend to use 15" rims if this influences which is better?????

Use chevy stuff, you'll pick up about 1.5". In addition to all you said, you will also need the backing plates...On the plus side, your calipers will work fine, and are the same part # in fact...Mike