what fluid to use in 8-3/4?

[68Valiant]

ok i got an 8-3/4 rear end and it has been stored for about 10 years with fluid in it. the guy told me to change it but didn't know what to put in it. what fluid should i use and how can i insure that it will work after sitting for so long? it turns and everything so it's not frozen up. but since the bearings etc. haven't had fluid in them for so many years how what should i do to make it work? do i need special sure grip fluid or something for a sure grip rear end or what fluid should i use?

[bsbn]

the best way to check the condition of the rear end is to pull the axels and pumpkin and inspect for rust or damage. if its ok reassemble and refill with 80-90 oil and mopar suregrip additive if its a 69 or older suregrip. the casting id # is on the pinion housing on the driver side

[451Mopar]

for gear lube I use the red-line synthetic gear lube.
Make sure to pull the axles and re-grease the axle bearings too.