Steves Camaro Parts - First Generation Camaro Differentials Data

Camaro 1967-1969
	10-bolt	12-bolt
Casting Number	3894859NF	3894860NF
Bolt Diameter	3/8	3/8
Ring Gear Diameter	8.20	8.875
Pinion Diameter	1.438	1.625
Axle Splines	28	30
Overall Dimensions:
Axle tube flange to axle tube flange	54 1/4	54 1/4
Between centerlines of spring seats	42 7/16	42 7/16
Shaft Length	29 33/64	29 9/16

Below is a list of positraction casting numbers. Gearing "up" indicates that the Posi Traction Unit is applicable to gearing Numerically Higher. Gearing "down" indicates that the Posi Traction Unit is applicable to gearing Numerically Lower.

Axle	Casting Number	Series	Gearing
12-bolt passenger	ED 32088	2	2.73:1 and down
	30140PM1	3	3.08 to 3.73:1
	EDB 30174	4	3.90:1 and up
Corvette	ED 32297 PW 3	3	2.73 to 3.70:1
	EDB 32298	4	3.90:1 and up
8.5 Corporate	410408N	3	2.73:1 and up
	410409N	2	2.56:1 and down
8.2 10-bolt	ED 32118	2	2.73:1 and down
	ED 30116	3	3.08:1 and up

Here we show you a picture with the location of the Casting numbers for both 10 and 12 bolt differentials and the location for the Axle Stamp. The graphic is a Courtesy of Steve Brown.

 

10 Bolt Vs. 12 Bolt

Which one is better? Great question. And the answer is: it depends. The 10 bolt is lighter and needs more power to turn. The 12 bolt is a heavy duty unit, much stronger, but is HP hungry and will suck your car more horses. Take a look at your aplication, and then decide wich one is for you. Usually, behind aBig Block Chevy, you´ll want to use the12 bolt axle.

source: http://www.firstgencamaro.com/rearend.html




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