I'm with highz on this one, I have not noticed any real difference in power with elevation change and most of our driving is above 4000 feet to as high as 12,000. I have the SOHC 4.0L. We just spent a couple weekends down at sea level and didn't notice any difference from home.
We bought our truck used a couple of years ago for getting a camper. Our previous truck was a 1994 ranger with the OHV 4.0. Put 200,000 miles on it and would have kept it but it was a stepside. We stuck with the ranger because I'm pretty familiar with them.
Interesting about the seats. We had buckets in the previous ranger and they were fine. Our current ranger is a FX4 Level II. It was the best truck of the ones we were considering purchasing, lowest miles, and the best deal. One of the features of this model is special off road seats. They don't look any different that the standard buckets but they are the most comfortable seats I've ever had in a truck. The Lady would get out and walk the rough sections with the old ranger. Now she rides.
The axles step up to the 8.8" from the 7.5" with the 4.0L and the brakes are bigger.
We changed the rear leaf springs to a custom set from Deaver. We had airbags and they worked well but we tend to get into rough remote places and were concerned about possible airbag failure. The springs were $650 plus about $100 shipping. It took us a Saturday morning to change the springs.
I weighed the truck empty with the end gate on, 4100 lbs. Installed the camper and loaded it up for a trip. It weighed in at 5000 lbs. We were not in the truck so add in 175 for me and 120 for the Lady. I figure fully loaded we are just under the door tag's 5400 lbs. max weight. We are minimalists- mountaineers and backpackers - and resist the temptation of adding more stuff.
Ah, but all this is kind of behind us now that the ranger is discontinued. It would be nice to get one with the 3.2 litre five cylinder diesel. Yeah, I'm dreaming.
T6 Ranger Pulling Locomotive