98 12v coolant temp sensor pigtail location

[Bob1983]

This is my first fourm post so be easy on me. Im in the process of 12v swap in my 99.

I have 98 12v pcm and engine harness. Everything was going good until I got to the coolant temp sensor.  I can't find a pigtail that goes to the coolant temp sensor. (I belive on 98 12v it moved from the back of the head towards the middle)Im wondering if anyone can tell me where does coolant temp sensor pigtail come out of the engine wire harness? Or is the ect pigtail in the underhood side of the harness? I also noticed I have no provisions in my fusebox for the fuel heater ect. Do I also need a diesel underhood harness?  I'm stumped. Any help is appreciated.  I have 20 trucks to look at but none are a 98 12v

[Bob1983]

I figured I didn't have the correct wiring harness. I'm currently swapping in a complete 96 harness. 

[Great work!]

Some older 12 valves have a small bypass hose near the thermostat. I think that hole is where the newer engines have the temp sensor screwed in. At some time a change was made so the hose wasn't required. The other 12 V style is at the back of the head, it is delicate they break easy.