I did this many years ago without removing the auto trans. I did loosen the other main caps so the crank would drop slightly. Removing the old seal was difficult. Had to use a long small screw driver to pry it loose and a wood screw to pull it out. While you are under there, you might as well check the rod and main bearings. Good luck
Hi, no need to loosesn bearing caps unless for a check. Doing this just allows for the possibility of dirt etc getting in or under a bearing shell.
Its a tricky job with the sump rails in the way but once the rear cap is out. You get a thin & long bit of wire, bend a very tight 180deg hook in one end, pull a curve in the wire, now feed the non hooked end thru the old seal in the block, if the curve you pull in the wire is of bigger radius than the seal you will not risk getting the crank surface with the wire.
Pull the wire right thru the seal then when the hooked end contacts the seal, turn the crank very slowly in the same direction as you pull the wire, the seal will feed thru very easily. Now blow the seal groove out with an air gun.
Refit new neoprene/rubber seal. Dont forget to remove the seal pin thats in the rear cap & seal the little hole with some quality sealer, (I use Ultra Blue)
Also offset the new seal about 1/4" in the cap & block in the direction of crank rotation to help avoid leaks.
Also the lip on the seal faces into the engine.