Renton's about 50 miles North of you...take 512N (or is it east?) to 167N and you'l hit Renton.
Place is called South End Auto wrecking (there is another of same name further south, no idea if they have a radiator shop though) and they will do it as you stand there and watch. /forums/images/graemlins/smile.gif
Temp switch usually goes in the intake, but the passenger side head has a por that is never used that will work as well.
These things are extremely easy to wire up...GM (and others) used plenty of different temp switches, less than $10 from Napa. You can get the wiring connector from the wrecking yards (if you stay with GM switch) and you can also get the relays from just about any GM late 80's+ vehicle, with the connectors as well. (wrecking yard again)
If you don't want the fans turning on when the truck is off, wire up one side of the relay to an ignition 12V source. You'll end up with four total wires: 2 small ones. One is the power from the rig that actually switches the relay, the other small wire goes to the switch. (the switch grounds, allows current to flow through, switching the relay)
The two large wires are even easier, one goes to the relay from the battery, the other large wire goes to the + on the fan. The - wire from the fan is just connected to ground. (frame, core support, etc)