Usually revised part numbers are higher.

- Warren

That makes perfect sense, perhaps my original post which noted that part number 3920627 was factory line correct and 3937930 was over the counter back in the day would align with the assumption that higher numbers would typically be for "revisions".

However saying this, a few members have early production cars with engine mounts 3937930.....???

Does anyone have any older 67-69 CAMARO MASTER PARTS CATALOGS to confirm?

Thanks..!

If it helps,I've got an original 1960-1969 seven inch thick Master Parts counter catalog,dated July 1st,1969,so that means it shows the most current #'s up to that latest date.
Here's what it shows for both of those mounts:

Now...that makes perfect sense....thanks for the information!