This pump was tested and taken off of a big block engine of of mine.  Has the support stud and nut on back side for roller camshafts with buttoms in gen IV motors. Nice set up!!

Guaranteed to work perfect or full refund.  

I have a video of the engine it was removed from, removed in 2023. Works great!!!  Even has a built in stud on back side to keep timing cover from flexing if using a roller cam with cam button.

This was an expensive high performance high flow pump when purchased new!!