Final Drive Ratios

[Ken H.]

Looking at GMC Manual X7425, page 0-2, for another reason, I came across
information I didn't know was available: The Final Drive ratio is stamped
on the flange near the right (passenger) side case expansion hole (the Big
one) of the FD. There should be a 3 or 4 character code, with the first
letter "T" (3.07:1 ratio), followed by "A"=January thru "K"=December ("I"
not used), and the date of manufacture during that month. EX: TA12 means a
3.07 made on January 12th.

BIG Q for Jim K.: Do Y'All obliterate that code when changing the ratio?
If not, no one should depend on it being accurate.

Ken H.

 

[jim kanomata1]

Ken, We have seen some but not that consistant.
We stamp on the machined surace where the cover is and mark 3.5 , 3.7, or
4.1 also LSD
Were the only one that do the ID .

On Tue, Aug 25, 2020 at 11:32 AM Ken Henderson via Gmclist <

> Looking at GMC Manual X7425, page 0-2, for another reason, I came across
> information I didn't know was available: The Final Drive ratio is stamped
> on the flange near the right (passenger) side case expansion hole (the Big
> one) of the FD. There should be a 3 or 4 character code, with the first
> letter "T" (3.07:1 ratio), followed by "A"=January thru "K"=December ("I"
> not used), and the date of manufacture during that month. EX: TA12 means a
> 3.07 made on January 12th.
>
> BIG Q for Jim K.: Do Y'All obliterate that code when changing the ratio?
> If not, no one should depend on it being accurate.
>
> Ken H.
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--
Jim Kanomata
Applied/GMC, Newark,CA
jimk
http://www.gmcrvparts.com
1-800-752-7502