External ID of T90C?

[pevrs114]

Gents,

Got my eye on the venerable T90C for my 49 3A.

I have read that they were used in 63-71 -3B and -5's, but were used with T90A1 cases.

Are there any external markings to determine, or do I need to be pulling the top cover and counting teeth?

Thanks

 

[scramboleer]

@diggerG

 

[diggerG]

I believe the T90C was the 2wd housing only. the difference is the rear bolt up. Some T90's were side shift as well. I think I have a T90
C I will look at it.
diggerG

 

[diggerG]

SO, I was wrong. The T90 D was the 2wd trans. I think the T90C was the different ratio for the 4.27 axles. That means different tooth counts on the main drive and cluster.
diggerG

 

[onlyonedr]

T90A has 18 tooth main input and 33 tooth cluster, T90C has 16 tooth main input and 35 tooth cluster. If the transmission is loose you can put it in first gear and count rotations. A T90A goes about 2.8 input revolutions to one output revolution whereas a T90C goes about 3.3.

 

[diggerG]

THe only down side on the T90C for a CJ3A would be that 1st and 2nd will be a little slower than the T90A. Probably not a problem.
diggerG

 

[onlyonedr]

THe only down side on the T90C for a CJ3A would be that 1st and 2nd will be a little slower than the T90A. Probably not a problem.
diggerG

The spread is larger from 2nd to 3rd so if you have an overdrive it can close that gap. Otherwise it will be quicker off the line but need a bit more revs in 2nd before shifting to 3rd otherwise it will lug somewhat. Using it without an overdrive will probably be annoying climbing hills since 3rd will probably be too tall and 2nd a bit short.

I am putting the T90C gears in my 3A with the 5.38s but will have a 25% overdrive.