Stamped on axle tubes

5

57 Handyman

Not-quite-so-new-guy
Feb 6, 2017
25
3
I recently acquired an 8.5 inch out of a Grand National. I don't know the year but it has 3.42 posi gears. The numbers and letters stamped on passenger side of axle tube are: 3TPG267. Does anyone know how to decipher these number or know what these mean? I would like to know the year of the GN for parts buying sake.

I will leave the story behind this rear end for another thread. Thank you in advance.
 
5

57 Handyman

Not-quite-so-new-guy
Feb 6, 2017
25
3
Thanks Mike...that was quick response. While I've got your attention, can you tell me if the rear covers for all 10 bolt rear ends are the same or does the 8.5" take a different cover? Several months ago, I bought a 10 bolt aluminum cover for the 7.5" but never installed it. Thanks again.
 
84GP455

84GP455

G-Body Guru
Jun 19, 2007
777
28
Methuen Ma.
I also have a 3TP stamped axle from an 87 GN and love it, but unfortunately the cover for a 7.5" wont fit on a 8.5" its different.
 
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5

57 Handyman

Not-quite-so-new-guy
Feb 6, 2017
25
3
Oh darn...now I need to sell this 7.5" cover and buy another one. Thanks 84GP455
 
ssn696

ssn696

Comic Book Super Hero
Supporting Member
Jul 19, 2009
3,646
113
New Mexico
The GN axle is a mixed bag. The center section is similar to truck 8.5s, but the axle tubes, hub bearings and brakes are the same as a 7.5. The one exception is the axle shafts themselves - 28 splines at the differential. If you lack a positracton, you can still take advantage of the 3.42s using a Powertrax locker that replaces the small differential gears. You can do this conversion yourself without changing the ring and pinion. If yours does have the Eaton-style limited lip with the clutches, they can be replaced. Put everything back in the way you found it and you should not have to change the gear alignment. If the differential bearings or ring gear have had better days, then plan to drop $1200 on a new limited lip and gears. Consider whether a 3.08 or a 3.23 might be a better solution to your driving plans.
 
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5

57 Handyman

Not-quite-so-new-guy
Feb 6, 2017
25
3
PontiacGP, thanks for your offer...rather than selling, I'm going to put it on my S-10.
 
5

57 Handyman

Not-quite-so-new-guy
Feb 6, 2017
25
3
No, I understood your offer completely. I was just clarifying what I was going to do and save both of us shipping costs to swap covers. Again, thanks.
 

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