I was hearing a rattle noise near the front of the engine and was just sure it was the timing bearing since I didn't change that when I changed the belt.
Turns out it was the water pump pulley:
It appears they can deteriorate from the inside out.
I am trying to adapt the one from my 1970 to the 1975 but have discovered the older one is about 3/8" deeper than the newer one.
Progress will be updated as I try to make this work
(I just hate having to buy parts)