I completed the fluid change and thought I would add my experiences to help others down this path: 1) took 4.25 pints of conventional hypoid 80w-90 oil to fill the differential after complete drain ( 71 skylark) 2) On my car I used a felrpro gasket 55028 to remount the cover. A tag in the box with the gasket recommended using a gasket sealant prior to installation (I used permatex #2) 3) Used Doo Wop suggested oil suction gun to refill the case; worked great! 4) Was able to use a few rags and some bake cleaner to clean up the inside of the case and the gasket mounting surface 5) Used a razor blade scraper (gently) to remove the bits of 40 year old left over gasket. The old gasket was pretty well attached after 40+ yrs.! 6) Re-torqued cover bolts to 20 ft. lbs Not a bad job to do under the car; just time consuming to scrape off the old gasket off housing and cover. Plan on half a day if your doing it without the benefit of a lift. Be sure and use jack stands. Good luck!
Nice write up. I just changed mine too. I used brake cleaner after scraping gasket off the cover. It really gets it oil free for the gasket. I also sprayed a rag with brake cleaner, then wiped the differential where the gasket will go too.
