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Old 07-12-2020, 07:48 AM   #9
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Join Date: Feb 2010
Location: Falls City, Nebraska "100 Miles From Nowhere"
Posts: 1,909
Re: Need help identifying my differential

The HA indicates it's a 3:73 gear. G is Chevy Gear and Axle, The 9 is the ninth day of the year and the 3 would be third shift. It is a GM Truck 12-Bolt that can be from 67-68 or 69...Might be a date stamped on the ring gear...That's not a factory panhard bar so it wouldn't be to surprising to find that the gear set has been changed and if your lucky you'll find a positrac has been installed. You wont know for sure unless you remove the cover and look at the stamped numbers on the edge of the ring gear. Judging from the crusty build up it's leaked a bit so it's a good idea to open it up and inspect it. You'll need a Fel-Pro #RDS13391 cover gasket for the GM 12T (Truck 12-bolt) and two quarts of MP SAE80w-90 gear lube. Any good synthetic will do nicely unless it's a positrac. A Posi requires 4 oz. of ACDelco LS Additive #88900330...
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