I just took mine off an 84 this weekend. Had to take off skid plate and replace half the metal in the bottom due to rust. While you have it off I highly recommend you take off the skid plate.
To get it off, just remove the lower bell housing cover, 7 screws. The screws attaching the oil pan are not tight if they were torqued correctly. Remove all the bolts. Place a 12 to 16 inch 2x4 on the side of the pan. Use a small jack to slowly press on the 2x4. Wedge it between the oil pan and frame. Do it slowly. It took about 3 minutes per side on mine before the pan let loose. No damage this way.
Remove all of the gasket material and then spray all of the corner areas with gasket remover. Scrap and spray until you get bare metal. The half moons are fun to get everything out. You need a narrow screw driver to get between the lips of them.
To remove the skid plate, clean the plate or sand until you see the spot welds. Mine were about 3/8" in diameter and there were 7 of them. Use a drill bit near the size of the welds and drill them out. With the plate removed check all of the bottom metal integrity. I could put my finger through one section. I cut out about a 4 x 5 inch section and replaced it. As I ground down the weld, I caused more holes as the metal was so thin. I finally got it all built back up and rewelded the skid plate using the same spot weld holes.
Test the pan with oil or gas if you welded it. Pour in at least a gallon and let set for an hour. Pick it up and check the bottom. I found 2 of my spot welds leaked even though they looked great.
To replace the pan, first seal the area around the skid plate with black RTV. Place a really good bead around the entire skid plate and build it up where there will be no chance of further moisture penetration between the oil pan and the skid plate. Clean the top of the oil pan sealing area and the bottom of the engine where the gasket goes with mineral spirits or brake cleaner. Wipe off and repeat. Make certain all four corners are perfectly clean or you will be doing it AGAIN. Place a very thin coating of RTV on both the oil pan and the engine. Check which way the gasket goes on the oil pan and then place it on the engine. There is very little difference so check it first. Install the oil pan and screws. The book calls for 61 INCH/Pounds, NOT foot/pounds. That is about 5 foot/lbs so you probably don't have a torque wrench that will set it. Go slow and tighten it snug all around. Cross tighten, setting each bolt 180 degrees apart to keep everything even. Just like tightening lug nuts.
By the way, you can't change the rear seal without pulling the transmission.
Best of luck. Sorry to be so wordy. Retired nuclear/analytical chemist. You only think you have met someone anal!!!
Jackrabbit
1984 and 1987 FJ60's.