Think it's just a good race block mopar puts on their parts shelf, kind of like the warranty blocks with the blank VIN stamping area.
Mopar had them on the shelf ready to go when someone needed one. I have a Warranty Block that came out of a 76 D-200 4x4 low miles, like no ridge. Got that one up and running now sitting in my 76 D100 Build soon to be on the road.
One check see if it has any vin numbers on the lower right front of the block and go from there.
