The control cavity .... I mean it HAS to have been designed for it. It's enormous and almost empty.

I'd like to add them to mine but I'm not a wiring whiz. It'd be simpler to pull the entire harness and replace it. But if someone has already done the work, I'd prefer to leave the wiring essentially as-is and just add/change what I need. (i.e. add the two pots only vs. replace the whole shebang)

Anyone?