Rear main seal is leaking on a Ford Mustang 2003 V-6

In order to replace the rear main seal u have to pull the transmission out to access it, u will need a special seal installer tool to install the new rear main "full circle seal", it u don't use the special ford tool the seal will leak again, also if there is a groove worn ion the crankshaft the crank must be repaired or replaced or the or the seal will leak again, so this is avery diff job, a 9 on the scale of 1-10 with 10 being the mos difficult.

The engine doesn't have to be removed however there is quite of bit of work involved with replacement of the rear main seal. if your going to do the work yourself a good investment is a chilton manual from o'reilly's,napa,etc. they run about 20 bucks and have diagrams for all sorts of repairs. also they will tell you the special tools you will need for various repairs.