Rear End Identification

Blaster · Nov 29, 2005

Please help? I have done an exhaustive search trying to figure out what rear end I have, year, make and type of vehicle it came out of. I thought I would put the info out again, these are all the numbers I have found on/inside the rear end:
(1) 2 PY G 81452....Stamped, Located on axle tube
(2) 254333....Raised, Located on opposite axle tube
(3) Carrier # GM 12 410408N....Inside stamped
(4) Pinion # GM 25 1978.....Inside stamped
(5) Pinion # 3984832-12.....Inside stamped
(6) Ring # 398483121578....Inside stamped
(7) E168...Raised, located on pumpkin
So far with the above info, I THINK I have a GM 8.5 in, gear ratio 3.42 limited slip unit. Additionally I counted the teeth and the unit had the silver tag on the pumpkin to use limited slip oil. However, I would like to know the year and make to facilitate in getting the correct drums/brake rebuild parts. Any help or advice would be appreciated!!!! Thanks. Blaster :

jimfulco · Nov 29, 2005

410408N is a GM 8.5" positraction carrier, 3-series (used with 2.73 & numerically higher gear sets). On the edge of the ring gear, there should be 4 sets of 2 numbers each, all close to each other. Two of those sets are the tooth counts of the gears, and the other two are the month and year of manufacture. For example: 41 12 12 73 would indicate a 3.42 ratio gearset made in December of 1973.

Measure the distance between wheel mounting surfaces and post it, along with a description of any spring brackets or control arm mounting points attached to the axle housing. If it has leaf spring perches, what's the distance between their centers?

If it has brake parts on it, what's the diameter & width of the drum's friction surface? What diameter are the wheel lugs, what's the bolt circle diameter, and how many lugs are there? If there are backing plates, what is the diameter?

Wheel flange distance of 60-1/4" and leaf springs would match a '72-up Nova. '70s Camaros are a bit wider, and also have leaf springs. Pickup trucks also have leaf springs, but the perches are on top and the lugs are bigger (1/2" vs. 7/16")

Blaster · Nov 29, 2005

Rear End Indentification

Thanks for the help!
(1) Wheel mounting surface distance, outside of drum to other outside of drum...60 inch's
(2) Spring pads on bottom, approx 5 inchs wide
(3) No sign;s of any control arm mounting
(4) Leaf springs perch's center to center 46.25 inchs
(5) Drum friction surface is 2.5 inchs
(6) Drum inside diameter is 9.5 inchs
(7) Outside drum diameter 12 inchs
(8) Wheel lugs 7/16
(9) 4.5 lug circle pattern
(10) Backing plate,(brake parts attach to it) I take that is the plate that is directly attached to the axle tubes it's diameter is 10.5 inchs
(11) Backing plate to Backing plate or end of axle tube to the other is 55.75 inchs.
Hopefully, I have answered your questions. AGAIN Thanks..Blaster

xntrik · Nov 29, 2005

Remeasure that lug circle.

On 5 lug wheels, Measure from the outside of one lug to the middle of the 3rd. should be 4 3/4 on a GM product.

Blaster · Nov 30, 2005

I stand corrected, the lug measurement is 4.75. Thanks

Rear End Identification

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