Re: 1964 cruise o matic rear Main question
A 64 Galaxie 289 will have a 2 piece rear main seal assuming no one has replaced the original engine. You'll have to drop the engine oil pan to gain access to the rear main seal. Reading your post it looks like you plan to pull the trans. That will not give you access to the seal. After you drop the engine oil pan, remove the rear main bearing cap and loosen the other main bearing caps to allow the upper part of the seal to be removed easier. The hardest part of the job is getting the upper seal out. Original seals are the rope type. Get a neoprene replacement seal for it. If you have a rope seal you can't replace the upper part without removing the crankshaft anyway. To remove the upper rope seal, after I've removed the rear main bearing cap and loosened the rest of the bearing caps (allows the crankshaft to drop down) I take a sheet metal screw and screw it into the old rope seal. You should be able to pull on the screw to get the seal out. Turning the engine over by hand (in the direction your pulling on the seal) sometimes helps. When you install the new upper part of the seal make sure the lip of the seal is towards the engine. Also leave about a 1/4in of the seal sticking out of the block. Install the other part of the seal in the main bearing cap(again with the lip facing the engine)with the 1/4in sticking out on the opposite side. The reason for doing this is so where the two ends of the seal don't end up flush with the block where it could leak. Install the rear main cap and torque all the main caps. Long winded, hope this helps.