Last 6 of my shelby 483221is this a normal marking of the vin on the heads?
Yessir. We all know they were "supposed to" be stamped on the back of the block, but sometimes the heads got stamped instead.
If the heads have ever been off and they were replaced on the opposite sides, it is possible for your VIN stamp to migrate to the front of the passenger side head!
I have a theory about why the heads were stamped, but it's only a theory.