While H1 shopping I've noticed on some '94-'96 models the a/c controls are the same as in the 97.5 and up (no a/c or recirculate button). Does this mean its definately had the a/c upgraded or is it possible the controls have just been switched out?

 

I suppose it could mean either but I would think that it would mean that the upgrade had been done. Ask and try the AC. If you have been in a non-upgraded truck you will be able to tell very quickly if the HVAC upgrade has been done or not.