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73-87 Chevy _ GMC Trucks => Engine/Drivetrain => Topic started by: 80stepsideguy on March 31, 2007, 04:06:00 pm

Title: rearend decoding
Post by: 80stepsideguy on March 31, 2007, 04:06:00 pm

Question,
i got 3 12 bolt rearends that are in my shop currently.All 3 have different numbers.But what is different is the rearend have the GM and 2 numbers stamped next to it. 1 has GM79 1 has GM81 the 3rd has GM70 .Are these the years these rearends were built?The GM79 rearend came out of a 77 chevy the GM81 is original for a 1980 truck we own and i dont know where the GM70 one came out of.Can anyone shed some light on this? Also is there anyway to decode these rearends by  a source online?

thanks
pat

Edited by: 80stepsideguy at: 3/31/07 3:06 pm

Title: Re: rearend decoding
Post by: joesgarage71 on April 04, 2007, 08:16:00 pm

Ther has to be more numbers stamnped in the tubes.

Title: Re: rearend decoding
Post by: shpark2 on April 19, 2007, 05:32:40 pm

I found TBK087W02 on the top of my passenger axle tube, 2WD '80 C15 - 12bolt rear.  I think first two are axle code, next is K for GM Canada, 087 is Julian day, W02 is production shift I think.  This is based on this thing I found for Buick, but I'm sure it's similar.  Anyone confirm this, and know what TB represents?  I know I should take rear cover off to make sure, but I got other priorities currently.
(http://i169.photobucket.com/albums/u210/shpark2/1968to1974BuickRearAxleIdentificati.jpg)