I should have taken pics or been more thorough in my examination, but I had visitors and felt guilty that I was in the back room doing this while they were in the living room waiting on me to "get dressed"...
Secret priorities, right?
In the pics at the top of this thread, the hole that you see on the new neck goes over the existing peg that is attached to the predator. (I didn't realize that till I pulled the old neck off. I thought the head peg slipped into that hole).
So that meant the peg that you see on the new neck becomes the new head peg (I thought that peg slips into the pred's body -- that wasn't the case). I pulled the old peg out of the head and set the new head on the new peg that came with the new neck.
Perfect.
Visually, the pegs look the same, and the area that the peg goes into the neck looks similar -- no rubber seal or gasket... maybe a few thousandths of an inch tighter at the rim.
Maybe that's all that it needed.
Again, if I get up enough nerve (or curiosity) I'll detatch it and take pics or measure the peg and compare neckholes when I get home tonight.
Fingers crossed, hoping yours works for you, Skull...