Magnum and Wiring Swap

Question... you mentioned you're using the 904. Did you wire in a speed sensor?
Thanks for the links to the PCM's, I'll check them out. Side note, I was scammed on a Mazda tech forum looking for a one year only PCM for a 1991 B2600i 4x4 that I had. After what seemed like a genuine conversation over the forum, I sent paid him for the computer to only hear excuses.
I haven't hooked up the speed sensor to the 904 yet. The Dakota used a gear driven VSS that fit in the place of a regular mechanical speedometer drive. I would like to keep my car's original speedometer, but I also need the VSS signal for the PCM and RWAL module. I have an idea of what I want to make for an adapter to drive both, but haven't got there yet. I am open to ideas and suggestions.