HI!... You don't need to pull the engine at all. Since your a 4X4, you'll need to pull the driveshaft, transfer case, tranny etc. Once the tranny is off, you will have to remove the flexplate (AUTO) OR FLYWHEEL (MANUAL). After that is done you will see a aluminum cover that houses the rear main seal (crank seal). Simply undue the bolts surrounding the aluminum cover and gently pry the cover off. It's is also held on my silicone. Pop the crank seal out and install the new one. Make sure to clean all the old silicone off the cover. Must be spotless. Re apply new silicone and reinstall the cover and TQ bolts to spec. Make sure you also TQ the flexplale/flywheel bolts to spec and use locktite on the bolt threads. They tend to come loose.
REAR MAIL SEAL AND HOUSING :
ALUMINUM HOUSING :
"1999" F-150 XLT SPORT, BUILT 5.4, all N/A.
354RWH.P/392RWTQ (no tune, yet) on 8 cylinders/ 1/8= 8.4, 13.60E.T (on 7 cylinders, broken ring in #5), 1.8 60FT.
"2007" FORD RANGER SPORT, EC, SB, 4X2, 4.0L. 1/8= 8.8, 13.83E.T