Salvage yard is not a good place to get a good 97 switch.
Better go new one and see what it does.
On the transmission shifting the speed sensor/or circuit will have to be working.
A good transmission capable scanner will give your the read out on all sensors and or transmission problems and or codes.
If it has codes post back code no.
For a wiring diagram of ign switch and transmission wiring you need a good factory repair manual or the all data sub.
http://www.alldata.com/products/diy/index.html