C900 Transmission Info Page
Over the years SAAB has changed the 5-spd transmission very little.
The key thing to understand is that any year 5-spd will bolt up to any C900 engine.
However, there are some small differences between them that you should be aware of.
The most common mistake is thinking that the internals of one tranny can be transplanted
into the case of another tranny. SAAB did change the internals a couple of times, so pay attention
to which two trannies you are swapping parts between.
Serial Number Designations
1979-1983:
type(G=manual)1st digit
version(engine combination)2nd digit
number of forward gears-3rd digit
primary gear ratio(see below)-4th digit
variant(stage of development)5th digit
1984 Onward:
GM=manual tranny-1st digits
GA= auto tranny-1st digits
transmission version-2nd digit
number of forward gears-3rd digit
primary gear ratio(see table below)-4th digit
variant(stage of development)5th digit
4th Digit: Gear Ratios for Manual Trannies:
| Primary Gear Ratio |
Input Gear
# of teeth |
Output Gear
# of teeth |
Final Drive Ratio |
| 4 |
31 |
30 |
.97 |
| 5 |
30 |
27 |
.90 |
| 6 |
31 |
26 |
.84 |
| 7 |
32 |
25 |
.78 |
| 8 |
33 |
24 |
.72 |
| Gear Set #8 was only available for the Autobahn and is very difficult to find today.
This set works great for modified engines as all the gears will be longer.
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Tranny Serial Number According to Year and Model
| YEAR |
Non-Turbo |
Turbo |
| 1979 |
G34402 |
G34602 |
| 1980 |
G34402
G45702 |
G45702 |
| 1981 |
G23404
G45704 |
G44604
G45704 |
| 1982 |
G34406
G45606 |
G45606 |
| 1983 |
G45606 |
G45606
G45706 |
| 1984 |
G34506 |
G45606
G45706 |
| 1985 |
GM34506 |
GM34506
GM45706
GM45X08 |
| 1986 |
GM45706 |
GM45706 |
| 1987 |
GM45X10 |
GM55X02 |
| 1988 |
GM45X10 |
GM55X02 |
| 1989 |
GM45X12 |
GM55X04 |
| 1990 |
GM45X12 |
GM55X04 |
| 1991 |
GM45X14 |
GM55X06 |
| 1992 |
GM45X14 |
GM55X06 |
| 1993 |
GM45X14 |
GM55X06 |
Changes made during the years:
1986 - Inner Drivers Changed. May be related to the change in internal centering.
1986 - Change to internal centering.
Mid-1989 - Drain plug removed on turbo boxes.
1990 - Drain plug removed on non-turbo boxes.
34xxx: Old Style CV Drivers
456xx: Old Style CV Drivers
GM45xxx: Solid Motor Mount
GM55xxx: Hydraulic Motor Mount
GM45x06: I don't know for sure, but I believe the very early boxes have incompatible synchro rings from other GM45x06 boxes.
GM45x08 is a 1 year box for the 85 900 turbo. It has an extra bearing on the input shaft. It is basically the same as the GM45x06.
GM45x10 and GM55x02 have internal centering, but parts are compatible with GM45x06 and 08.
GM45x12 and GM55x04 has internal centering large pinion bearing. NA cars 89-90 early boxes have drain plugs. Internal parts are not compatible with x10 or lower versions.
GM45x14 internal centering large pinion bearing and revised shift forks. Internal parts are not compatible with x10 or lower versions.
x12 and x14 internal parts cannot be transplanted into x10 or earlier cases.
If you have more interest in the SAAB manual gearbox, the manual is still available from the dealer for around $20.
There is really no substitute for the book. The front of the book explains all the part numbers and what application they had.
Even if you never plan to rebuild a box, the book is neat to look at.
Here is a link that goes into great detail on how to do an automatic to 5-spd swap:
 - Learn how to swap your crappy auto 3-spd for a 5-spd transmission.
Many thanks to those who contributed this information!!!
If there is some wrong information or I've missed something, please e-mail me with the updates!
E-Mail Jeff
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