Speed sensor wire

My brother is taking out his RB1 nav/radio out of his Grand Cherokee and giving it to me for next to nothing. I know I have to do some modification to the center bezel/mounting and will need the adapter for it (two 7 pin to 22 pin adapter). It needs to be connected to a speed sensor wire in order for it to work properly. I wanted to know which wire would be the correct one to splice into for this setup. The RB1 will be going into my 01 with AW4.

My understanding is that the RB1 gets its speed signal via the BUS wire. I am not sure if simply connecting this wire to a VSS (speed sensor wire) would do the trick. If your XJ has that BUS wire then thats what gets connected to that single connector coming out of that special harness you are referring to.

I am actually curious about this myself as I am looking at getting a 99 XJ Limited and would also be interested in installing this unit. Let me know what happens.