[Tf175]

       
The shift control in my '86 is different to what you have , but probably functionally similar.  I sourced parts for the shifter at the trans from T.H. Anderson as well . Contacts , etc , which activate the leds.  The interlock system ( prevents starter operation in gear) is under the dash , consists of relays ( 2 , I think) . There may be a schematic in the manual or other literature that came with your coach . 
Before I replaced the contacts I had a situation where I would have sworn the neutral light was on when shut down.  On start up , the D light was on,  starter locked out . Had to move the shifter lever at the trans to get going.
The remote start is in rear passenger side compartment , follow precautions carefully if you use it .