My SSEI does not have a coolant level switch.
When I needed a radiator, the GM dealer also needed to know which style of tranny cooler line connection I had – apparently two different types were used.
The aftermarket one I ended up with included all the necessary plugs and adapters you need for any combination of level switch and line connection style.
Just a final update... yes, the radiator was very bad. My good friend at the shop put it under pressure and pow! He was surprised that I made it as far as I did without incident. Warranty paid $400, I had to pay $50 toward the rad as they had a $275 limit on the part. So, it was indeed the tank at the base of the raised mounting for the fan. He noted no stress as did I.