The 22RTE truck had a thermo spout with NPT (or close enough) fitting built in. You could drill and tap them.
The downside is that if you don't have enough water flow, you'll read hotter than you are.. but that maybe good for your purposes.

Another alternative would be to use the existing gauge sender. As long as you have a high impedance circuit that you're using to drive your warning light, it shouldn't impact that reading on the gauge... You'd need basic knowledge of analog electronics.

22REturbo.net




1988 4Runner
22RTE core, turbocharged, megasquirted...