[mr52pickup]

I guess it's time to ask for help. I'm trying to ID a GM 12 bolt rearend. The closest result I come up with is a '72 Suburban on an Ebay listing. Maybe one of you folks can come up with some info. Here are the facts:

On the axle tube: MJ0411W with an E stamped slightly below the MJ letters.
On the diff housing: GM5 on one side, N1 ( or I ) 3896839 on other side.
On gear inside: 3817778 11:41 GM 2-67 2

Thanks for the help.

[jimfulco]

11:41 is the tooth counts for the gears. 41 divided by 11 = 3.73 gear ratio. The 2-67 is the manufacture date, February, 1967.

What does the rear cover look like? If it's mostly round with a wave bent into it, it's a 12-bolt car-type rear end. If it's oddly shaped, fatter on the left side than the right, it's probably the truck-type 12-bolt.

Is it set up for coil springs or leaf? If it's leaf, are the perches on the bottom or the top? What's the width, axle flange to axle flange?

[mr52pickup]

It's about 62" from between wheel mounting surfaces. Give or take an inch, the axles aren't in it right now.
There are no spring perches on it presently. It is possible they could have been on the top; there are locations were the metal is different looking than the rest, possibly someone ground off or cleaned up the area.
Regarding the cover, it is not quite round, with the longest top-to-bottom length off center to the left, in line with the gear. It is the same cover I see in all the truck parts catalogs I have.
If this leads you to believe this is from a truck, then let me offer this other tidbit of info: I ordered wheel bearings and seals from LMC truck, with the supposed application of being for a 67 - 72 truck, and they are too large. I don't expect you to know all your part numbers, but in case you do, the bearings are #R1559-TV. This is the reason I'm trying to ID this thing, to get the right bearings. I did a quick search on the Autozone website, and they too come up with this part number for the 67-72 truck, so I'm pretty sure LMC truck did'nt send me the wrong thing.
Thanks again for your time.