ORIGINAL: proptop
I think George might be on to something?
Since we're all having a guess, mine would be that the owner modified it to interchange with a Tee Dee .010
BL...when/if you win it, you can measure the bolt spacing to see, aye!?
Sadly it escaped me by only a little. Hopefully the new owner may be a reader of ths thread and be able to share that info with you.
The good news is that I did get one from the same seller for less than this other 'stud'!
I suppose the bidder may have thought this engine to be more valuable somehow. It did throw me at first. I was the next highest bidder on this one and obviously underestimated its worth to this one other person. Cest la vie!
Robert