<VV> 1964 wiring diagram question

[aeroned at aol.com]

I'm getting close to getting the revised, colorized wiring diagrams finished for 1964 car, but I've run into a bit of a problem. If you look at the engine wiring diagram in the shop manual, there are three engine temperature "sensors" at the top of the page, to the left of the coil. At first, I thought the middle one was the oil pressure switch, but it's located near the generator. So, could an EM guy please explain what these three senders are for?
 
Thanks,
Ned