Just figure on replacing both...then you don't have to worry about it. I believe that if you drop the center link you can replace them both with the engine in the car.
Pan gasket will show seepage down the sides and/or front of the oil pan (separate gasket for joint at timing cover); rear main will show contamination of clutch or oily (not trans fluid) torque converter and ring gear.
Vikki 1969 Goldenrod Yellow / black 400 convertible numbers matching
As I was crawling around the Firebird, I was amazed at how dry the pan was after 18 years. The next time I'm under (I was too lazy to roll out, get the sockets, and roll back under) the car, I'm going to check the bolts. If you're luckey, maybe you can get away with snugging up the bolts.
I've done an oil pan, twice, with the engine in the car. As Vikki says, I think that if you drop the center link, the pan will slide out.
If the car was parked clean and hasn't been started, the pan should be dry. A leaky pan gasket doesn't leak when it isn't running, nor does a rear main. The oil level is not to the top of the pan. The only way to find out if you have a leak is to pressurize the rear main, and splash the pan gasket.
Vikki 1969 Goldenrod Yellow / black 400 convertible numbers matching
I think the only way to tell is to remove the converter cover (if auto) and wipe the entire area down with a dry rag then start the car until you see drips on the floor. Then shut off the car and crawl back under there with a flashlight. At least that's what I have to do. When I had the engine out I put a brand new steel pan on in place of the chrome after market pan the leaked real bad. I wiped all surfaces with laquer thinner and used the cork seal in the groove at the back with 3M super adhesive and snugged the pan on overnight. Then a thin bead of Permatex 2b on block to gasket and snugged and let sit. Then a real thin smear on pan and just snugged up the bolts. No leaks on initial startup. Have run the car a few times and no leaks. The other day was letting it idle and reved it a couple of times. Small f'in oil puddle. RRRRRRRRRRRR! Maybe the bolts just came loose a little? Please?
