T-5 Speedo drive gear

Has anyone here run a T-5 in A 63 Fairlane??(obviously someone has)
I am just finishing one and not sure what speedo gear to run.
It's a 3.00 8 inch rear with a 91 T-5 from a 5.0L,and I'm using the stock speedo

 

It depends.

There are at least two different drive gears on the tailshaft. The driven gear you need will depend on which one you have - if you can see inside, look for the color. Yellow and Black are the two I'm familiar with.

Here's a chart:
http://mustangpartstech.com/SpeedometerGears.html