ID rear end in my 1967 C10

[Peanut74]

Ok, I have been trying to figure out what rear end is in my 1967 C10 long bed. The passenger side axle tube is stamped "HA04 27 W" but none of those codes show up on any information I have found. Does anyone know what it is or point me in the direction to get the information.

What I do know for sure is that it is a GM truck 12 bolt by the diff cover. In addition I am assuming the "W" means assembled in Warren, MI.

[michael bustamante]

theres a search tab in the blue bar above. type in something like rearend ID or axle ID or something like that. there was a good thread on here a couple years ago that had a link to the codes on the axles and locations.
it all depends though on what the truck came with originally.
My 67`s have had 3;73 gears with 250 inline 6s and both granny trannys and 4 on the floor, tranny. one had originally had a 327 with a turbo hydromatic tranny and that came with a 4;11 posi.
theres also a way to lift the rear end and count the rotation of the drive line in relation tp the wheel spin. someone here will know how to tell you how to do that
most likely though a 3:73 or a 3:08

[Peanut74]

I did find the one post that had a list of all the codes but mine was not on there. This truck has been sold a number of times so I'm in the process of trying to figure out what has been done to it. From what I can tell it has not been changed out but that is an assumption on my part.

I did more cleaning on the axle and found some casted numbers. On the front right side it has "GM58" and on the front left side it has "NI 3896838". So the search will continue.

[GASoline71]

Pull the cover and count teeth. Also the ring and pinion gears will be stamped what their respective tooth count is. Do a little math and boom... gear ratio! Plus, then you'll definately know if it's an open diff or a posi-traction diff.

No doubt the gear oil probably needs to be changed anyways.

Gary

[Peanut74]

Thanks Gary. The more I dig the more it looks like I will be forced to pull off the cover and count the gear. How can I tell if it is positraction?

[LockDoc]

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Did you look at this thread?

http://67-72chevytrucks.com/vboard/s...d.php?t=578793

All you use is the HA..... HA for '67 is 3:73 non-posi. Don't pay any attention to the c14 designation, I think it is a misprint and should say c10.

LockDoc

[Peanut74]

Thanks LockDoc. I did look at that thread but was also trying to use the rest of the stamped numbers. AKa I made it more complicated than it was.
My truck has had a number of owners each of which made changes to it. So you can imagine the things I'm running into figuring out what I have.

[LockDoc]

Originally Posted by Peanut74

Thanks LockDoc. I did look at that thread but was also trying to use the rest of the stamped numbers. AKa I made it more complicated than it was.
My truck has had a number of owners each of which made changes to it. So you can imagine the things I'm running into figuring out what I have.

There are not many of these 50 year old trucks that have not seen numerous modifications and upgrades done to them. That is part of the fun for me, figuring out how things should be on them.... Keep at it and ask questions on here when you need to. The members on the board are always willing to help.

LockDoc

[GASoline71]

Originally Posted by Peanut74

Thanks Gary. The more I dig the more it looks like I will be forced to pull off the cover and count the gear. How can I tell if it is positraction?

Look at this post from my build thread. Here is what the guts of a posi-traction unit look like. Springs and clutches. If all you see is gears in there it's an open diff.

http://www.67-72chevytrucks.com/vboa...&postcount=125

Gary

[Peanut74]

Thanks for the pictures GASoline71 they are a big help. I did jack the rear end up and spun the wheel. One went clockwise and the other counter clockwise so that confirms its nonposi. Also, tried to confirm the gear ratio but that didn't go well. Kept getting conflicting results. But based on the cracking of the rubber bushings its the original hard pan.

So I've come to the conclusion that its the original rear end. I would open it up but will do that after it gets back from the frame shop. Started the trucks disassembly and noticed that the frame rails were not vertical and looked a little bit off. So I want to have that checked before I start making mods to it.

[michael bustamante]

if the rear end has the trac bar still on it to center it, chances are its the original.