when i purchased my car the front seats that were in it werent even e body seats. i [built] a set from scratch. the lower sections of the seat frames came from a 71 challenger. in between the springs and the padding, i found an electric strip heater. it appeared to be factory;and looked lke it had been there since day one. was this a common item for e bods? it was only on the passenger side. where would the switch have been?