Getting ready to pull the rear end out of my 69 bird for clean up and repaint. While I have it out I figure I'll drain the oil out and put fresh in but was wondering what weight it takes. It's an original rear end
80/90 hypoid gear oil. If you have a Safe-T- Track [posi] use Safe-T-Track gear oil, if they still make such a thing, or 80/90 with the limited slip additive.
What's a safe t track look like? I know there's a small plastic piece on the top of the rear end about half way down towards passenger tire that I'm not sure what it is. I haven't gotten my book yet. I was guessing it was the fill spot for the lube
I thin you're talking about the vent on top of the tube. You drain it by removing the cover. You fill it through a plug on the lower part of the pumpkin. To know if it's safety track (AKA posi), turn one wheel and if the other wheel turns in the same direction then it's a safety track and requires special oil or additive. If the other wheel turns the other direction then it an "open" read end and uses regular gear oil
Safe-T-Track is the name Pontiac used for it's limited slip differential. Some other brand's names are: Twin grip; Twin Traction; Traction Lok; Power-Lok; Positive Traction; Sure Grip; Positraction. Most just call them Posi or limited slip.
As Bob says, lift both rear wheels off the ground and with the transmission in neutral and the park brake off, turn one wheel by hand and if the other wheel turns in the opposite direction you have a non posi. If they both turn in the same direction you have a posi. Check that vent while you're at it if it's plugged you could build enough pressure in the axle housing to cause an oil leak. Been there, done that.
You could pull it out. Make sure the axle hole it not stopped up. Blow into vent portion that goes into axle and see if you can blow threw it. If all that checks out, it works.