4x4 Guru's....I need some help

[superchevy]

I've got my '72 K25 down to the frame/susp and am trying to determine what is going on with this truck. First, is the front track supposed to be wider than the rear? Asking, because the front track on this truck is about 3" wider than the rear track. This leads to my next question....I'm wondering if the Dana 60 rear currently attached is the original one to this truck. Wondering, because the rear springs are not original...notice the rear hangers have been moved rearward, and welded...not riveted...to the frame....spring eye to spring eye is 56"...cleaning the frame today with degreaser, I ound that written on each leaf spring in salvage yard ink was " 74 C20 Chevy "...so the original 52" springs were replaced with these 1974 56" springs. The D-60 measures 53 1/2" from backing plate to backing plate....is this a stock '72 width, or do I have a '74 D-60. See the pics.
Appreciate any help on this issue.
Casey