T-5 Interchange
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T-5 Interchange Information

Often I am asked by a person that has picked up a used Mustang T-5 transmission if the one they have found will fit their car.  The T-5 has undergone many changes through the years and yes, many of them can swap.  I will leave the 2005-2010 T-5 out of this, as these T-5s are drastically different.

These are the 6 basic swap groups.  
If you stay within your group there will be no problems!

bullet85 through 89 V-8
bullet90 through 93 V-8
bullet94 through 95 V-8
bullet94 through 98 V-6 
bullet99 through 04 V-6
bulletany 4-cylinder T-5

When venturing outside of your group these are the Items to look closely at.  If you can find a suitable work-around, have at it!

bulletThe length of the input shaft
bulletThe pilot diameter of the input shaft
bulletIs there a neutral switch on the top cover
bulletIs the speedometer sender gear-driven, or all electronic
bulletThe number of teeth on the internal speedometer gear
bulletThe location of the cross-member on the tail housing

Length of the input shaft
There are three lengths of input shafts.  

bullet83-93 V-8, 
bullet94-04 V-6 /94-95 V-8, 
bullet4-cyl.  

The 4-cyl shaft is about a quarter inch longer than the 83-93 V-8 shaft.
The difference is considered negligible, but the pilot bearings are also different sizes.

The 94-04 input shaft is about 11/16 longer than the 83-93 V-8.  A 94-95 style bell housing is needed to go with a 94-95 length input shaft.  These Fox and SN-95 V-8 housings can be swapped, but be careful.  Your aftermarket headers may no longer fit because the clutch forks extend at different locations!  The V-6 Bell housing is NOT interchangeable with the V-8 because it needs a 164t flywheel and a V-8 uses a 157t flywheel.   

Sometimes the input shaft can be changed to obtain the correct length to allow for a transmission swap.  Remember that the throwout bearing sleeves are different lengths also...

bulletIf the gear on the input shafts have the same number of teeth, they can be swapped.
bulletBoth input shafts must have use the same type of pocket bearing between the input and the main shaft.  COBRA and T5Z inputs use a Caged, Tapered bearing.
bulletA World Class input shaft can be put on a non-world Class transmission as long as you use the World Class type synchronizer ring, and vice-versa.
bulletA 4-cyl, input shaft will never interchange with a V-8 input shaft because the tooth count is different.  
bulletThe 85-93 V-8 input shafts will work with the 94-04 transmissions and vice-versa. (V-8 and V-6)
bulletWhile the 4-cylinder shaft cannot be swapped, a 4-cylinder transmission can be put into an 83-93 Mustang with the right pilot bearing (Do you really want to do this?)

The Pilot Diameter of the Input Shaft
The V-8 pilots are 0.668 and the 4-cyl pilots are 0.590 inches.

Is there a neutral switch on the top cover?
The 85-93 V-8 Mustangs all need the neutral switch.
Some of the 4-cylinder models within this range have the switch and some don't.
The neutral switches are not on the 83-84 and the 94 and newer T-5's.
An 85-93 V-8 Mustang will run without this switch.  Some don't notice its absence.  Others discover that the car surges, or doesn't idle correctly.

Is the speedometer sender gear-driven, or all electronic?
While only the 83-93 Mustangs use a speedometer cable, the speedometer sending unit is gear-driven from 1983 through 1998.  A 99-04 Transmission will work with a 94-98 Mustang if a signal converter box is used.  

The number of teeth on the internal speedometer gear
The 83-89 transmissions have a 7 tooth internal gear and the 90-98 transmissions have an 8 tooth internal gear.  This 8 tooth gear is generally incompatible with differentials such as the 3.73 or the 4.10.

The location of the cross-member on the tail housing
The 99-04 Mustang cross-member is located about an inch and a half further towards the rear.

This article was last updated on 07/27/2012 .