1990 Jeep Wranger, 4.2 6 cyl.. main seals?

You must drop the transmission to do the real seals and you must remove the timing cover and drive gears to do the front ones. You do not have to remove the crank though. You should invest in a Haynes or Chilton manual for this vehicle. It has step by step on everything you will ever need to do to this Jeep.