Heck, changing the rear axle was one of the FIRST modifications I did, and that was back in the fordranger.com days when I even knew where my Chiltons manual was!
First rear axle swap I did on the '90 Ranger was from the 3.08 to I think 3.73 gears, some guy was local and was selling a 7.5 without any brakes for $15 (yes, $15, said it made noise, I didn't care with 3.08's and being in college). So I figured that out in my mom's gravel driveway... Did the axle swap without bleeding the brakes, pulled the axle shafts then the backing plates, tied up the brake assembly then put the "new" axle under there, worked fine...
Sounds like you know about the diff tag on one of the bolts, as said earlier, it's a complete crapshoot, to make things weirder for whatever reason most explorers seem to have limited slips? For some reason the '91 I had with manual transmission had an open with 3.55's so I swapped it to 3.73's with limited slip instead of using that axle on my '90 and ended up putting a lunchbox locker in it for a while...
For what it's worth, the driveline bolts are 12pt 12mm, if you heat them up some with a propane or butane torch and put a wrench on them then hit the wrench with a hammer that should get them loose... if I go to a junkyard going after a driveline or axle I bring a butane torch if I remember, the yellow loctite they use is kinda mean... From there it's just the U bolts, sway bar (if equipped), diff speed sensor (just unplug) and the center brake hose (you can just cut it if you don't want to deal with it in a junkyard) then the shocks. I used to have the wrench/socket sizes memorized but it's been a while...