Go to a wrecking yard. Pop the hood on an mid '80s or newer GM. If you look in a Cad or full size Olds or Buick, you should find a dozen of them in different styles. Some are round and they also use a couple of different square styles.
I like the ones mounted with plastic pull-pins.
Pick ones that are wired to a fan or anything that runs full time for the higher amp ratings. In other words, look for ones with two or three small wires and two large wires.
Don't worry about getting a bad one because they are very reliable. Get several.
Most have their wiring diagram on them with a part number. I have had good luck finding many of the part numbers on the internet to check specs.
