Determining rear differential gear ratio

Kube

Original poster
Member
Aug 27, 2014
2
I have a 2006 Saab 97x that I need to determine the rear differentail gear ratio. I assume this can be done via the serial number.
If my assumption is correct, might anyone be able to to advise me what character I need to look at and how to apply that to the ratio?
It is an AWL equipped vehicle.
Thanks!
 
May 5, 2013
434
Not sure about the saab but is there a list of codes in you're glove box? If so, one code is for you're gear ratio.
 

dmanns67

Member
Apr 3, 2013
32,979
Ohio
You should have your data plate on the inside of your glove box. Use the search function on this forum and search for "rpo codes". Thread was started by Illogic. Basically it translates all of the rpo codes.

Best way to do it is take a picture of the data plate in your glove box, then you can reference the picture for the code.
 

The_Roadie

Lifetime VIP Donor
Member
Nov 19, 2011
9,957
Portland, OR
If the rpo code sticker is missing, just do an empirical test. Put a chalk mark on the drive shaft and a tire. Drive straight while somebody counts driveshaft revolutions and tire rotations. Ten tire revs will come from 34, 37, or 41 driveshaft revs. Simple.
 
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AtlWrk

Member
Dec 6, 2011
674
To that point can't you just put up one rear wheel and count wheel vs driveshaft revolutions? Or would the differential double the number of driveshaft rotations...or halve it...?
 
Apr 26, 2014
53
When I did an engine swap I needed the ratio on the included front diff. I called the dealer parts dept. with the VIN from the doner truck and they told me the ratio.
 

IllogicTC

Member
Dec 30, 2013
3,452
I'll post the RPO information here.

GU6 - 3.42 axle
GT4 - 3.73 axle
GT5 - 4.10 axle
G80 - Whichever axle as listed above, with the Eaton Locker mechanism inside.
 

Kube

Original poster
Member
Aug 27, 2014
2
IllogicTC said:
I'll post the RPO information here.

GU6 - 3.42 axle
GT4 - 3.73 axle
GT5 - 4.10 axle
G80 - Whichever axle as listed above, with the Eaton Locker mechanism inside.
This was most helpful. I want to thank you and the others that offered good advice.
I have, no big surprise, the 3.73.
Much obliged guys!
 
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May 5, 2013
434
No G80?
 

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