vibration at 25-40 mph

The mount looks normal as they are made with those kinda raged looking holes.
If cleaned off you could check to make sure the rubber flexes a little if you yank it around a bit. (bet it does from the looks of it and that is normal, but of course you will have to bolt it up first.
Watch for cracks or tears in the two solid rubber sections if you can.

That's a common place for bolts to fall out of, so when you put them in use a little blue Locktite on the threads to keep that from happening.
Personally I like only big lock washers between the bolts heads and the mount metal AND blue Locktite. :D

Sorry, don't recall the size of the bolt shaft but I know the heads of them are 5/8 so they must be 7/16 course thread? X 1 inch long (the threads, not the total length with the bolt head)