looks like you can just use a single pole double throw switch, from the diagram it looks like there are 2 elements.. hi and low. so power from the car, into the center prong on the SPDT, and one element to each outer prong. and then the common one in the seat to ground on the chassis. anything i missed? you could also wire in indicator lights if you wanted. anybody know what that switch looking thing is in the center of the heaters? pressure switch? or
