Is there a difference from a 72 to a 73 340

My guess is that 70aarcuda nailed it...but is it a sloppy fit on both sides? I would guess that the passenger side shouldn't be a problem if you had 318 mounts.

IIRC some folks have temporarily stacked washers to allow the use of 318 mounts with 340/360 blocks. If you need to get the car moving, that might be an option but I sure wouldn't leave it that way.