well if we're obviously talking Square Body cab, year range 73-87 the cabs WILL BE THE SAME with only minor differences to be noted:
-the door's interiors will change '77ish; the early 70s door panels changed to the newer late 70s to 80s door panels. SO if you get an 80s cab, your door panels WILL fit and work on the doors BUT there will be extra holes showing. either have the holes, patch them somehow or get 70s doors (LMC has OE quality steel reproductions, $290 a pop)
-IF you are doing the front clip also, it does change between 73-80 and 81-87 bold styles. Trim will not work (not that the military truck will i think), fenders change along with hood, bumper, etc.
-KEEP IN MIND if your truck is a 4wd, or a stick shift, and you get a donor cab without holes cut in the floor (say that was a 2wd automatic), you'll have to do cut them, OR cut your old hump out and rivet/weld into the new cab. Or the reverse (patching unwanted holes)
-Dash structure may be slightly different, being its under everything and should be clean, a cut out and weld in will work IF necessary (it's possible)
Other than that I'm 99% confident EVERYTHING else is WILL indeed work. Wouldn't hurt to see some pictures, I know the military did Square Body military trucks with the M1008, M1009, m1028 in the mid 80s, but a 70s one? I'd love to see that old girl. HOPE I HELPED