Just checking to be sure. and what do I need for making the lockup solenoid function? Can I run it off a window or rpm switch?

I'm thinking I could use a momentary pushbutton on the shifter to make sure it's in third or higher as the trigger for the window switch. Then the window or RPM switch would send the signal to lockup the trans at the given engine speed.

 

it all depends on what wiring is inside

it is easy enough to do what you want