heater AC instructions/manual where do i find?

[THE BOSS]

i bought the complete heater A/C system form a guy that has owned his 72 blazer sence 1973, he turned it into a sand drag race truck, removed everything saved it all and i bought it all. (in boxes, lots of boxes)

where can i find a factory service manual, book or site with help to put the cab back together the way the factory had it. my 72 truck had some missing parts and not right in some areas. it was a AC truck originally.

i only need help with the in cab stuff, the engine compartment i have done, or will have done soon.

all the duct work, cables..........