Last thing was to get the Speedometer working. G56 trannys do not have a speed sensor. Dodge started taking the speed off the rear axle in 98. My truck is a 97, but does have an ABS sensor in the rear axle.
It was not my idea, but saw it in a couple of writeups. The idea is to use a Dakota Digital (the company, not the truck) SGI-5 interface unit to pick up the rear axle signal. Currently Dakota does not list this as an application, but I figured it was worth a try.
The writeups use a four wire hookup. Power, Ground, Input, and output.
For input, I picked up the ABS signal from the back of the OBD2 port under the dash. The wire to tap into is red with a purple tracer.
For output to the speedo the writeups say to tap into the white wire with an orange tracer at the bundle under the dash next to the parking brake. I was unable to find the wire there, so I pulled out the cluster and found it easily to the right there. I tapped into it and tried driving truck......nothing.
Long story short is that the writeups did not say that the white wire with orange tracer needs to be cut completely, not tapped into. Once a wire is run from the back of the speedo (still the white with orange tracer one) directly to port 3 it works great. Switch 1 and 2 are left down, 3 and 4 up.
I mounted the unit to the brace under the panel at bottom of the dash. It is accessable while driving with panel off for fine tuning. Push and hold the buttons down for adjustment. I tuned mine in a few seconds with my GPS. Cool thing is I can easily retune with a push of a button for different tires or a gear swap.
Only thing I noticed with this setup is it runs 1-2 MPH fast under 25 mph. After that it is dead nuts accurate.