another rear axle id request

[oldman3]

Working on a 68 GMC pickup. I know the front end has had a 73-87 front crossmember, etc. installed. I am assuming he also installed the rear axle.
These two pics show that the old shock brackets were cut off and the 68 style welded back on. Numbers and letters on the housing are TFA then G057. I tried doing a search but I kept getting a note that I didn't have space for information. Any help with this is appreciated, just want to know what I have for ordering new parts.
Thanks....Jim

[andrewmp6]

Take a few pictures of the center of it front and back and measure its width them two can id one faster then anything.

[SS Tim]

Jim,
As I have almost nothing for later reference material I'm going to have to wing this some. The best answer appears to be a 73 C20 3.21:1 ratio axle. Using the GM parts Wiki (my last resort fallback) gave me a couple of later front axle applications also in 3.21. If you wish to chase these down more here is a link to query "TFA".
http://www.gmpartswiki.com/query

The G057 code is the plant and julian date codes
in this case GM Gear&Axle plant and the 57th day of the year (057) (26 Feb.).

[oldman3]

Finally able to get back to the shop today. For andrewmp6 here are a couple pics showing front and rear of axle. The axle width is 63-1/2" mounting flange to mounting flange. Backing plate to backing plate is approx. 57-1/8". Brake drums are 3-9/16" and brake shoes are 2" wide. Tube size of axle is 3".

[oldman3]

A big thanks to John and Tim from the site for their information, especially the link. I removed the back cover and found that it is a 16 to 41 tooth ring and pinion with equals to a 2:56 ratio. I've also shown a couple pics of ring gear (not clear hard to see numbers), and were old shock mount was removed from axle. Also showing the upper shock mounts on the frame. The width of axle makes me think it's a 71-72 but not sure. The search goes on ..Jim

[oldman3]

will only allow one pic at a time, old mount to right of current mount.

[oldman3]

last pic upper shock mount at frame

[aggie91]

since it is a 10 bolt axle, it is most likely from a '79-'84 model C-10.

The 10 bolt did not come in the 71-72 trucks....

[oldman3]

Thanks Aggie91 that's some good info to have. Anyone else want to chime it, need all the info I can get. The owner of this truck doesn't know anything about what was done to it before he bought it. I just would like to fill in the missing info if I can. Thanks to people on here I have the info I need to replace parts, etc.. I would just like to nail down the year if at all possible. Thanks....Jim

[aggie91]

Can you post all the numbers off of the ring gear? That might help determine the year. Also, any numbers on the center casting of the rear end housing...

The TFA was used on many years...I will have to look at the 10 bolt that came out of my son's '82...

[oldman3]

Aggie91 here are some pics with the numbers on the cast center section


Drivers side is B201

[oldman3]

Drivers side 1254333

[oldman3]

Passenger side GM36

[oldman3]

Tried to get a pic of numbers on ring gear, but I have a cheap digital camera and for some reason I get it in focus and shot, but it comes a blurry. Anyhow the numbers on the ring gear are: 2GM 3984822 16 41 2 81. Not sure but the 398 number is part number
the 16 41 is ratio 2:56 and the 2 81 number would be Feb 1981. Will wait and see what you find, thanks again....Jim