That is your old transfer case shift lever,you would pull out the FD button to get in 4WD.Then you could use the lever to shift into low range.Pretty cool system,I used to use mine all the time and it worked great.
That diagram is right on the money,One of the only things I see different is it does not have the FD button on there as it must be from a later year.
I have mine here,I am looking at it.Mcwinery I could send you a photo copy via snail mail if you pm me an address.My camera is not loading pics. onto my computer rt. now or I would snap one and post it up.
I am sure you can order a owners manual from Spector$$,It's kind of fun to have.Looks like the diagram that was posted up might be from SOR.
If You want to keep It operable you Can keep the FD and T/C shifter with a 2F/4 speed & early T/C I Did,
If you lengthen shifter Relay rod by welding in a piece of 3/8" rod I think Its like 4 and 3/8" IIRC and use the original 3 speed T/C High Low shifter,
The FD Vacuum shifter valve can be used also, Below the Vacuum Shifter Valve cut the two steel Vacuum piping @ the bend in the tubing below the firewall on the passenger side and make up the difference of the longer Transmission with two short pieces vacuum hose to make the bend to the Transfer case vacuum shifter, It was pretty EZ and looks clean too.