[Calum]

I'll take a picture of the dimensions I'm referring to.

Yea, its a potentiometer. Thats actually part of the factory Nissan ecu, the wires go under the daughterboard. You turn the pot on the ecu to switch into diagnostic modes, and its directly connected to an ADC channel on the mcu. Weird, but Nissan used that for ages. There's actually a spot on the board for a pcb mounted pot instead of the large pot, and Nissan stuffs either the pcb pot or panel mount pot on different runs of the ecu, I guess based on whichever part happens to be cheap.

On the interconnects, take a look at the products offered by a company called Samtec. Digikey reps them and they sell direct. I think the BBS line is a board to socket, or you could just use standard terminal strips if your not using a socket.