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jr38special

Just bought a rear end from a 74 Nova with automatic trans, no posi. What would the rear end gear ratio be?? 308,370 ?? thanks JR new guy

jr38special

WOW I didnt realize I asked such a tough question,,,,,,,,,,, no replies!!

jamesmartinez

Have you checked the numbers on the differential?

James

Ted W

Here are the ratio codes for 1974. The code is on the back of the axle tube, drivers side.

JA - 2.73 open

JB - 3.08 open

JC - 3.42 open

JM - 2.73 posi

JN - 3.08 posi

JP - 3.42 posi

MikeKy55

Just to expand a little. Since the axle is out, pull the cover and count the teeth on the ring gear as well as the pinion gear. Divide the pinon number into the ring number. That will give you the ratio. Gears got changed after these cars left the factory. So the only sure way is counting teeth.

Well the Auburn Gear differential can take a lot of abuse. The standard rear end in '74 was 8.5" and you can tell as the bottom of the center of the rear end has 2 "tabs" at the bottom of it. On the rear that's currently in your car...10 or 12 bolt (count the number of bolts that hold the cover on)? If it's a ten bolt, it's the same rear end size, 8.5". It probably looks strange under there if they left the ears where you would put bushings in for the rear links (A-bodied cars were coil-over rears) on the housing!

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