If you look at the top right gold bolt in the pic, you will see there is a stong metal structure to it.

Early pumps don't have that strength bar, and this is where they fail




more important to check, rather than part numbers

Andy K is right, but it’s not a readily visible part. This is an early oil pump, you can see how flimsy the tensioner attachment point is compared to later versions.

Click image to enlarge