Haha I had to come look because I couldn't remember. It's a 3 wire sender.

 

Hook a ohm meter to the back of it and find someone with some calibration equipment ( a reference gauge basically and a hand pump ) and pump it up. I have a 2007 GMT900 4.8 I could snag the sender out of and try this if you want. I have the reference equipment lol. The only thing will be if I can find something to allow me to connect my pump to the sending unit.

 

I was digging around today in the manufacturers books and components guides. The resistance specs are not listed for the oil pressure sending units. I made a phone call too, but nobody could find a spec.

Then I went back and read your OP again (third time's a charm, right).

You're adding an aftermarket oil pressure gauge to your Colorado with a swapped V8, right? Because your factory cluster does not have one.

You posted 2 different Autometer gauges. They will only work with their own sensor, and the sensor comes with the gauge. I don't believe the Autometer gauge will work properly or accurately with the factory GM sending unit.

Now, for the sake of discussion, and possibility that I'm wrong (has happened before ), let's look at the Autometer gauges for a second. The cheaper one, #4327, uses a one wire sending unit for a short sweep gauge. Not likely at all to work with your 3 wire sending unit. Now take a look at your expensive one, #4352. It uses a 3 wire sending unit, and looks very much the same (connector-wise anyways) as the GM part. I pulled an Autometer sending unit off the shelf, and took a pic of it next to my computer screen with the GM sensor pic.



So if you're going to gamble, that's the one to try.

 

Ddaaaammmmnnniitttt of course I need the expensive one. It's never ending with this thing.

Thank you SOOO much for all the time and research!!