Rear Axle Codes

[aggie91]

For the RAX W3512

I get:

RAX - 1972 3.73P (I believe the P stands for positraction)
W - Warren, MI assy plant
351 - 351st day of the year, Dec. 16th (1972 was a leap year, otherwise it would be the 17th)
2 - Second Shift

[First c10]

Karl thank you for the info I appreciate it.
That was fast
Scott

[SS Tim]

RAX 72 KS-KE10 3.73 posi

[First c10]

I wish it was complete but all I got was the housing, axles and an open dif. but it was free so I will just assemble with new parts. Thanks Guys

[LockDoc]

Originally Posted by First c10

I know this is an old thread but didn't want to start a new thread.

I picked up this rear end to rebuild for the truck. I know it is a 12 bolt but can someone decode the stampings please?

Look up the RAX in this thread:

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

LockDoc

[1969KatyTX]

The code on mine is HC1217W on the axle tube with the casing code of NF3890838 on the front of the pumpkin... can anyone give me some insight to what I have? Is there an easy why to determine the spline number with out pulling the axles?

[LockDoc]

Originally Posted by 1969KatyTX

The code on mine is HC1217W on the axle tube with the casing code of NF3890838 on the front of the pumpkin... can anyone give me some insight to what I have? Is there an easy why to determine the spline number with out pulling the axles?

Use the "HC" and look at the code lists in the link I posted in the post above.... Pay no attention to the C-14 it should be C-10.

Lock Doc

[aggie91]

Originally Posted by 1969KatyTX

The code on mine is HC1217W on the axle tube with the casing code of NF3890838 on the front of the pumpkin... can anyone give me some insight to what I have? Is there an easy why to determine the spline number with out pulling the axles?

from the factory, your rear was a 3.73 positraction. If it is a '65 or later GM 12bolt truck rear end, the axles should be 30 spline. If you are unsure, the only other way to check is to pull out an axle and check it...

[Michael_e]

Found this thread while trying to get info on a axle I bought for a project. It's a dually axle from a cab & chassis truck. it is supposed to be the narrowest Chevy/GMC dually axle. It's from a early to mid 80's truck. I tried all the links above but they didn't get into the 80's trucks. So... Here are the codes-
KMR G0 342, I think that last number is a 2 as it wasn't stamped real well. Hope someone can help, or point me to where the info might be located. I'm really after what year truck this might be from so i can get all the right bearings, seals, and brake parts also.
Thanks,
Mike

[sharkskinman]

65 3 tree, 230, stepside

HA 08 15K??
Ratio? Posi?

What can I switch out a little more highway and still keep 6 lug?

[66BigBackWindow]

I searched the threads and found that the rear end in my 1970 parts truck (TDE 1219 W2) is/was a 3:07 built on Dec 19 at Warren and the 2 is 2nd shift, right?

[Fitz]

Originally Posted by rsavage

Does anyone have the info to decode the axle codes that are stamped on the top of the left hand tube of the rear end for all years (67-72) including Burbs? I found some info but it only included 67 and 68-nothing for my 1970 trucks.

Go here:

http://www.348-409.com/differential.html

Every code for 1959-1970 C10's are listed.

[c104life]

I have an 71 c10 swb step side with 307 4 speed, my spid says positraction rear A. Looked on the rear end the only thing i could find was NF3896838 could someone tell me what type of gears do i have?

[66BigBackWindow]

http://www.348-409.com/differential.html

Every code for 1959-1970 C10's are listed.

Went there. TDE code is not listed.

[tom7254]

can someone decipher these codes. I know its a 12 bolt. Casting 3896839 GM83, axle tube stamping TBT 219 01. Thanks

[LockDoc]

Originally Posted by tom7254

can someone decipher these codes. I know its a 12 bolt. Casting 3896839 GM83, axle tube stamping TBT 219 01. Thanks

What year is it? By the code it looks like '71 but there is no TBT for '71. Double check the TBT letters and make sure that is correct.

LockDoc

[tom7254]

Double and triple checked. It is plain on the tube TBT. I couldn't find that code either. Closest was a 1971 TPT, but you can clearly see it is a B

[tom7254]

I bought the front and rear diffs out of a 1981 Blazer and am putting them in a 1964 K10 short box. I had to move the spring perches in 1" on each side. The 1964 spring set up is 40.5 " and the diffs i bout were 42.5"

[LockDoc]

Originally Posted by tom7254

Double and triple checked. It is plain on the tube TBT. I couldn't find that code either. Closest was a 1971 TPT, but you can clearly see it is a B

Originally Posted by tom7254

I bought the front and rear diffs out of a 1981 Blazer and am putting them in a 1964 K10 short box. I had to move the spring perches in 1" on each side. The 1964 spring set up is 40.5 " and the diffs i bout were 42.5"

That would explain the 01 in the date code then. The code lists I posted only include up to '72 so you will have to find the later code lists. Maybe in the "PartsWiki" links that SSTim posted above.

LockDoc

[LS-K]

Reviving this old one...

1982 SWB K10

Rear Axle Tube reads “KBD G356”

Casting #1254333 on diff ball driver side
Casting on top left side of diff ball is “L141”
Casting on diff ball pass. side is “GM36”


Any help is greatly appreciated. Parts store can’t seem to find the correct brake drums I need to get this baby back on the road.
Posted via Mobile Device

[sara76]

Can anyone help me identify the axle in my 1970 C10?
On the Axle Tube it is stamped HC 06 0 8 W
................................................E
I am thinking it is a 3.73 Posi out of an early truck???? The Dropped E has me confused. I think that HC is a Posi 3.73, but on my axle tube it definitely has a E, but it is dropped down one Row from the rest of the stamping.

[pjmoreland]

Based on the charts LockDoc posted in the following thread, it looks like HC is 3.73 ratio with posi. 1970 was a transitional year where they went to a wider overall rear end width. Since the HC code is listed in the 1969 chart, I'm wondering if your housing might be the narrower design. I may be wrong about this, but I believe the wider design had GM54 cast into the center housing, whereas the narrower design was GM51. That's how it was on a wide 1970 housing I sold recently vs. a 1968 housing I purchased to replace it. Measuring the width of the rear end would be the conclusive way to tell.

https://www.67-72chevytrucks.com/vbo...d.php?t=578793

Copied from the thread below:

axle width is 55.5 wide with 30.5 long axles on the narrow rear end. earlier rear end
axle width is 57 wide with 31 5/16 long axles on the wider rear end. later rear end

http://67-72chevytrucks.com/vboard/s...d.php?t=640514

[sara76]

pjmoreland-Thank you so much !!