Inline 6 water pump question.

[CJ Loeffelholz]

Good evening, fellas.


I noticed my 1970 C10 with an I6 engine was making some racket, and I identified the water pump bearing as the culprit.

I ran to NAPA to grab a replacement pump, picked it up and it looked correct. I painted it, pulled off the old one and then noticed the offset is different.

The one I pulled off has a 3-7/8 offset from the mounting surface to the mounting surface of the fan pulley - and add to that an 1/8 spacer that was stuffed in there too. The NAPA one only has a 3-1/4" offset.

In the interim, I yanked the water pump and fan off of my 65' and installed them, which out to get me by until I can identify what pump I need.

The engine is stamped F0318TCK. Can anyone give me any advice as to what pump I should be using? Is this the correct engine for a 1970? I figured it was the original 250, but maybe it's not. Or maybe I got the wrong part from NAPA.