Head Case

A recent find was this "Sweet 16" Barbie head on this "Ballerina" Barbie body.. or at least a body with "Ballerina" arms.

This head

This body

Of course, I've never seen a Sweet 16 Barbie head on a Ballerina body in any kind of a box or package, but they turn up often enough mated this way in the wild.

Sweet 16 Barbie had "Mexico" style arms, called that because they were mostly produced at Mattel's Mexico factory (as opposed to Japan or Taiwan or elsewhere.)  Sorry I don't have any quickly available right now for a picture (while I'm thinking about it, lol.)

These arms had small nubs holding them on and they fell off easily.  Heads were still fairly removable and shareable during this time period, so I can only imagine that plenty of Sweet 16 dolls lost their arms, and their heads were transferred to Ballerina bodies.

Remember, if you see a head on a body that seems unusual, there's a 99% chance this is a child being creative with their toys and not some rare prototype or special doll.  Unless it's sealed in a package, there is just no proof.