Right now in my 87 with 22re, R151F, 4.10 and 31" BFG MTRs, I can run 70+ all day long.  But on hills, it's between 3rd and 4th, and holding 60 easy.  But pegged to firewall.  That's empty though.  With several hundred pounds, I'm struggling on keeping the rpm's up.  And that is with stock exhaust, and a "open" cat. 

In July, I'm gonna keep a journal to see what happens, cause I'm going to Yellowstone.  Taking two rigs, since our van won't hold all of us.  So, I'll get to see what I do at different elevations.   Cause I'm at sea level right now.

off subject but if you have never been to montana/wyoming (i live here in MT) or yellowstone your gonna love this place!! i highly recomend getting up to glacier park if you have enough time. Something you can only see here in MT and my favorite place in the world!! then you can really test how it does at elevation