need help again. bought a junk yard rear end, and dont trust the axle numbers, since the gears may have been changed. says its a 75 camaro by the numbers stamped on it. (2PH G085) which indicates its a 2.56 non locking '75 or '77 camaro.measured everything and it will fit my '70. Would like to go to a 3.08 or 3.23, ( Ill be doing alotof hiway driving and gas prices are high) but am unsure ofwhats in it. dont want to replace them if I dont have to. the ring gear numbers are-2GM 3984822 16 41 3 81anyone have a reference book that can tell me what they are??? thanks in advance....

 

That is a 2.56 gear, which is a goodhighway gear, but lacks a bit in the acceleration department. Any thing lower than that will reduce fuel mileage, unless you install an overdrive.

 

great. thats what I needed to know. Thanks.

 

rear end gears are not called planetary gears. planetary gears are the gears inside of an automatic transmission.