This is probably one of the dumbest questions you have ever heard but is there such a device that can turn a mechanical speddo setup into a electrial one.

 

It is not a dumb question and yes there is. Check out the guys who have done the T-56 swap. Try a search under "T56 speedo question." There are a few ways to do this but it requires you to buy more than the tranny.

 

shifty, i was having that same problem too, i found a company called TERF.COM , that is in the process of making an adapter that will adapt a mechanical driven speedo connect to a 4L60E trans. the guy told me about 2-3 weeks till its done. hope this info helps.:rockon: Good Luck to all those LT1 swappers out there, time to spank some mustain ***!!!

 

http://www.skulte.com/T56.html Has info about the T-56 swap, and under Speedometer Calibration it has a link for a box that does just what you described.
Hope that helps,
-Corey