Water temperature gauge question

[Jayschevy]

I recently purchased a 71 C10. The previous owner had the water temperater going to a seperate gauge instead of using the gauge in the instrument cluster. I decided that I wanted to use the one in the instrumnt cluster. After removing the cluster I found out that the cluster's circuit board was damaged and thats probably why the temp gauge did'nt work.
I have a new cluster on order but my question is how do I hook up the water temperature to my new instrument cluster. There doesn't seem to be a place in back of the cluster to screw the water temperature probe into.
Any help would be appreciated.