OK as it say's above, when I got my shiny new limited slip diff from Tran-X I was a happy bunny until I wanted to fit the plastic drive wheel for the speedometer.
It wouldn't fit the Tran-X casing is bigger than a standard GM unit.
So I phoned Tran-X and asked how do I get my speedometer to work, the answer was you can't. But I need to M.O.T. the car, sorry we can't help you.
.
BUT here's how to .
You will need your old speedometer drive wheel,a good knife and some metal epoxy glue.
Ho and a Tran-X diff.

Ok start with your old diff and drive wheel (ring) cut the plastic drive wheel along the line already in the wheel. In the photo below I've marked it in red.





You should have two rings from the old drive wheel.
In the photo below is the inner part which you no long need.




Take your Tran-X diff and newly cut drive wheel and clean well must be no oil or dirt




Then using the metal epoxy glue fix the speedo drive wheel to the diff case.
Put the epoxy on both inside the drive wheel and outer diff case.
See photo below.




Below is the old GM diff and drive wheel and the Tran-X diff with drive wheel plus the knife I used. Also is the off cut from the drive wheel.





In the next pic is the Tran-X with speedometer drive wheel in place.





In the next few photos is a quick and easy hand tool I made to help with removal and fitting of the diff.










I hope this may help some of you.

I AM NO EXPERT SO IF YOU TRY THIS YOUR SELF IT IS AT YOUR OWN RISK.