did they offer a glove box manual for the 1972 GMC sprint or did GM use the 1972 chevelle one like they did for the 1972 El Camino?

Yes, the Sprint did have an owner's manual. I've looked around but I don't think anyone is reprinting them.

any way I could get a photocopy?

As 72Sprint stated they did make a GMC manual for Sprints and I have not seen any reproduction. My Sprint came with a 72 Chevelle manual and not the GMC one. My Sprint was built in Feb so not sure if it was to early for the GMC manual or not?
I picked up one from eBay.
If you need a scan of it LMK.

All of the GMC Sprints from '71 to '77 came with a GMC Sprint Owner's Manual. They are very similar to the Chevelle/Camino Owner's Manuals, except that they have the "GMC/SPRINT" logo on the cover (and a few slight changes inside). The '71 has a brownish cover and '72 has a purple cover.

Mr. Carr is it still possible that my Sprint ended up with w 72 Chevelle one? I thought with the lower production numbers of the Sprint maybe not all of them got GMC manuals and that's why I ended up with a Chevy one.
I guess that the GMC one could of gotten lost but I got a lot of original paperwork with the Sprint. In fact one of the build sheets was folded inside of the manual.

Were the manuals put in at the factory or was it a dealer prep thing?

Brian:

A scan would be great. that way I know what to look for.

No problem engineer.
Just send me a e-mail so I can reply with the image as you do not have the e-mail option active with your profile.