I am asking because I found a valve cover with what I thought may be a factory tach plug. When I took the plug out, I found that it has a small step that goes thru the seal, ie where the shaft went thru.
On the ones I made, the oil is kept out by an o-ring on the hole outside the seal portion. So I concluded that it was likely homemade.
But then the thought occured to me that perhaps they not only put in a plug, but may have left the drive out as well.
If this was a factory plug, then it would not fit on a bike with only the tach cable removed.