Thanks to everyone for the input. Looks like I can get the 15337-300-010 plug Mark suggested at DSS. That leaves me either using the smaller 14mm hex Cap or my original one which appears to be solid with a 17MM head as Chris suggested. Not a show stopper as the part can be changed after my build is complete if necessary. I'll keep my eye out for an early solid 17mm hex Cap.
In case you're wondering, I'm guessing mine was damaged when someone installed an engine guard on the bike. Just a guess.
If anyone wants the 15337-300-000 - Plug, Oil Tube, well it's
rare according to Chris so big bucks!
Just kidding. If anyone needs it, just let me know.