Actually its really easy to change a real seal. I've done it about six times between my two 89 wranglers.( 4.2L ) All you need is the rear seal, an oilpan gasket, a tube of mega black or some sort of gasket maker, and about 3 hours. Start by draining your oil. then take off your oilpan. one side of the seal is inthe rear of the pan. Pay attention to how they go in. (It is possible to get it in backwards and it leaks like crazy.) THen take a punch or something and drive the top half out of the block. After you replace the seals, put your oil pan gasket on. THe front should be ok but the back where the edge of the rear seal is has always been about an eighth of an inch too short for me so I put the mega black inbetween the rear seal and the cork gasket. Be careful not to get it on the part of the seal that touches the crankshaft. Just put it in between the flat part of the seal and the cork gasket. THen put your oilpan back on and reattach any gas lines you had to move. Don't forget to put your oil back in. THen give it a try. You will know if it works about the time it gets to operating temperature. Good luck.
89 YJ upgraded with 95 Chevy LT1 small block, NV4500 5spd, tera low 231 SYE, Custom built crossmembers and skids, 2003 Corvette Electron Blue paint, 3 inch custom spring lift with 2 inch shackles, 2 inch body lift, locked 8.8 with discs, 4:10's and 35's, spray lined tub, and a few other unmentionables