I was hoping for more than an emoji from you. Cat got your tongue?

Unlike merziac I'm not a Merz expert, but it's my uderstanding that serials starting with JM were only the bikes he built for himself. Most had other letters, the initials of the customer it was built for.

Bike in question is not a Merz, the reason I'm confident of that is the seatstays are attached too low on the lug. While that could be because the builder couldn't source seatstays that were long enough for this Gigantor, Jim was (and is) too much of a perfectionist to allow that. He'd have come up with some other solution. I dunno, splicing in another section of tube to make the stays longer maybe.

Just guessing really, but a Merz is more perfect than this frame in some other places too. I mean it's finely built, just not Merz-level.