Slant 6 Water Pump Rebuild

I did that once. On a different straight 6, a Ford 300.
When I put the clutch fan back on (one of the first direct thread onto the pump shaft ones I ever worked on) I fought it coming off as tight as it was. I gave it that "last little tug" and snapped the threads off the wp shaft. Not wanting to "eat" that wp, I pressed them both apart and pressed it back together in the new housing with the new seals/ bearing, and original shaft. Never had an issue with leaks or squeaks the whole rest of time that guy owned the truck .