Rear axle ID

[BR3W CITY]

The weather has broken enough that I can get back out in the garage, but I need to get some info together.

My rear axle is a 12-bolt, and I was told when I got the truck that its a 3:73 rear end, with posi. I have the code " N 3856525" stamped into the gusset. I can't seem to find a site to decode this. Is this a truck or car rear end?

Rear brakes are drums, it has 5-lugs, and its on my 66 with trailing arms. I couldn't tell if the rear end ever had leaf perches, since it was cleaned up and painted by the po. Its got Moser axles, and I was told it was a 3:73 posi rear. Anyone have a clue what rear this might be?
Thanks!

[john]

On a 12 bolt, you will find the axle code on the pass side tube. Look about six-eight inches out from the punkin, there will be some letters stamped in the tube on the top side a little bit to the front. Post the letters and we can decode them. Hard to say what is actually in there on an old truck without pulling the cover and looking.

[Captainfab]

The code on the axle tube is only going to tell you what GM put in that housing. If it is known to have Moser axles, the only way to know for sure what else is inside, is to pull the cover and have a look. It's easy to do and it'll only cost you a cover gasket and a couple quarts of gear oil. Chances are the oil needs changed anyway.

[BR3W CITY]

Ya, I have no problem pulling the cover. I'm not really worried about whether or not its a 3:73, I'm more concerned as to WHAT the rear end was out of. The pass axle code should tell me that correct?

Thanks

[ka_jd7and1]

A Yahoo search of the number you posted brought up a few pages with '64/'65/'66 trucks that had that rear end. Can't tell you for sure if it's original to the truck.

[BR3W CITY]

I found the other code stamped in the axle. It reads HA 05020 W.

[john]

HA code was used in 1969 C-10 12 bolt. 3:73.1 ratio

[BR3W CITY]

Thanks very much john!

[ChuckyC]

The code on the differential that I just purchased is HA 0110k, can someone help me to identify it?

[BR3W CITY]

What I can find shows a 67-68 truck rear end with a 3:73 non-posi
http://www.gmcpauls.com/67-72_chevy.htm

[ChuckyC]

thanks man, I really appreciate it. i have been searching all over and couldn't find anything.

[BR3W CITY]

haha, I only saw your post because it popped up on my old sub'd threads, since I was the original poster. You really found an old one too!

If you google your axle ID, no info will come up, mainly because the specific code may not match enough others. If you look at the GMC pauls site, and a few others, you can start to get the decoding system down. Main thing is to look at those first to letters, the "HA"...which corresponds to the 3:73 gearset rear. The only trouble is finding the correct ledger to compare it to.

[The Rocknrod]

I have a WC 6 17. DOes that mean a Posi 3.73?
And what does the 6 17 mean?

[1963c-10]

WC = 3.73 posi June 17

[wolken]

My 12 bolt reads TBA W001 2

Can someone please decode this for me I have been looking all over. I broke and axle and I know this rear end does not belong to this truck.

[Captainfab]

To get a new axle all you need to know is the number of wheel studs and the bolt circle, the length plus the spline count.

[wolken]

Have you been to a parts store lately? The last time I went in to get a clutch master cylinder the kid actually asked me if I had an automatic or manual... It would be much easier if I could tell him what the axle was in or at least give them a year.

[Captainfab]

Yes I have and I certainly would not even consider going to one of the chain parts stores to get an axle for an older truck. Get the info I mentioned above and then look online and see what you can find. You must have some sort of idea what the differential is? What year of truck is it in now? Is it a 2wd or a 4wd? What makes you think it is not original?

Take a look here.

https://www.yukongear.com/partslist....SpotlightID=14

[71GMCguy]

I have a 71 gmc c15. that the po put an earlier model rearend in it because it is a 6 lug rearend, I'm trying to find out what year the rearend is. So I can order 5 lug conversion axles. stamp code is THA W032 2. Any help would be great!

[Captainfab]

This is the only axle code listing I have saved but it only goes up to '67.

http://www.67-72chevytrucks.com/vboa...d.php?t=327764

Being 6 lug it could be a '63-'70 2wd or a '71-'87 out of a 4x4. IMO the easiest thing might be to measure your WMS to WMS and then you will know what length axles you need. All '63 to early '70 12 bolts have a WMS to WMS of 62". So you would need axles that are 30.5" long.