Speedometer correction needed?

[500magnum]

I just replaced my rear-end gears with a 3.23 ratio in my '89 3/4. The originals were 4.10's and after that were 3.73's and now 3.23's. The speedometer is off quite a ways now. I have a 400 turbo with the electronic head in the tail housing. What options do I have to correct the speedometer? The only thing I see is possibly replacing a gear inside the housing that the electronic sensor reads off of. How do I know how many teeth gear I need if this is the case or are there other options?

[More Power]

www.superlift.com (http://www.superlift.com) produces a device that allows re-calibrating the VSS (Vehicle Speed Sensor). It is installed in the VSS signal lines between the VSS and the vehicle electronics. It's adjustable to compensate for changes in gearing or tire size.

Jim