Option Z62 info please?

[SLS]

As the search continues I have run across another '71 shortbed (115" wheelbase)....1/2 ton version. 350/350 combo is non-matching....although the options sticker says that is what the truck left the factory with. The block casting date is 1976 and heads are from 1973. It also has a 12 bolt differential...but I don't know if it is original or what gears it carries. This one is a much easier fix (I hope), although I will be replacing practically all of the sheetmetal and interior. It is/was a 545 White/light yellow truck with a 623 Parchment Custom Cloth interior.

Listed on the glovebox sticker is a load of goodies (PB/PS/AC, Tinted glass, gauges, dome & cargo lamps, heavy duty front and rear springs, blah, blah, blah). The last option is:

Z62 Custom Comf and Conv Equip


The truck has Cheyenne 10 DELUXE badges (not attached due to ongoing bodywork...but holes in fenders mate up).

Does anyone know what this option (Z62) actually consist of?

Also, is there a way to identify the differential....and what is supposed to come on the truck originally? Are all 12 bolt diffs posi-traction?

Thanks for sharing any wisdom about these matters!