I began putting my engine together after getting it back from the machine shop. The machine shop installed a new Melling P/N M-66C oil pump. I noticed the pump has one less mounting bolt and there is an "uncovered" area on the block. According to the Melling catalog it is the correct part number. Has anyone experienced this?

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"Just think of all those Ford owners who will someday want an automobile."
John Francis Dodge

I'm trying to post photos but they don't post

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"Just think of all those Ford owners who will someday want an automobile."
John Francis Dodge

Yup. Look around,lots of posts about the 5 bolt vs the original 6 bolt pump on the site
Lota are suggesting that you pull your original apart, inspect everything close, clean it out good and if it looks good to reuse your original oil pump.
Also so you can reuse the original oil pump drive gear that's already worn into your camshaft drive gear.

I thought about that but the original pump seems to be seized. I'm not so concerned about the one less bolt as I am about the hole. I wish I could post the photo.

_________________
"Just think of all those Ford owners who will someday want an automobile."
John Francis Dodge

Double Post

Don't need to post pic, we've seen em
It seems all the semi recently manufactured new pumps for these engines are made that way.
I redid my engine late 21/early '22 and at the time I found a new but OLD stock oil pump for mine on eBay of all places. It's 6 bolt like the originals were. Many have used the 5 bolt pump it don't appear to hurt anything.