I'm assuming a G-body here?
Two bad switches themselves seem suspect. Usually only one may be bad, but I have to admit, I did have one lock side bad and the other the ulock side was bad (contacts were toast).
The relay is up behind the kick panel on the passenger side.
But if you DO happen to need switches, you want GM or aftermarket? Do you need to remain GM stock parts?
20734310 is the GM number. Search Ebay with that number and you'll get a plethora of aftermarket versions as well.
The relay is p/n 20306055 and they don't make that in aftermarket parts that I can find. Borg Warner had one that was R4732, and it looked identical down to the bracket like the GM one. I can't find that BWD makes those anymore from their website.
You'll need to find a G-body one, as B and C list different part numbers. I don't know what the difference is. 81 A-body and 82-88 G-body. Monte, GP, Regal, Cutlasss...all the same.
Relay gets power from a Circuit Breaker (rear defogger is on this circuit too if equipped) and the switch sends signals to the door lock actuators via the Dome Light fuse (20A).
Here's an Olds G47 diagram. Other G-bodies should be similar.