If it is indeed the rear main seal leaking, the transmission needs to be removed. Not something you’d want to do if you’re not mechanically inclined. First you need to be sure that’s the problem because it’s a $25 part but for a shop to do it, you’re looking at most likely $1500 in labor if not more. There are other places for leaks that could result in oil dripping in that area. One is the oil pressure sender. Another is rocker covers. The other that comes to mind is the valley cover. I might be forgetting one, others will chime in. It can be difficult to determine where a leak originates from, it can run down from above. You can start by cleaning the block with a pressure washer and degreaser and then get a borescope and inspect after you run the engine a bit. The sender is pretty inexpensive, you could try replacing it as well as the rocker cover gaskets and see if anything changes. The valley cover is kind of hard to tell but if you look with the borescope at the rear of the block near the firewall you might be able to tell. Others here have dealt with a valley cover leak. Good luck, let’s hope it’s not the rear main.
