well, look for the obvious ... rust, signs of a wreck, etc. Drive some figure 8s to make sure that 247 is in proper working order, especially if its quadra-drive (likely is). Check the air vents for proper flow, I hear the blend doors arent fun to fix, itd be nice if that was already done.
that should have the 30/44a axles, seeing as how its claiming to be a 4.7HO. All wjs have the 30 front, and you can look at pics of the center of the 35 and 44a to see the difference, then crawl under and have a peak... if its clean, you can read off the tag on the differential. Should be 3.73 gear ratio with the 44a, assuming its stock. Kinda odd that the owner would only debadge the 4.7HO off the tailgate though, but it can happen