Trumpet King

The serial number is ML 0999, but this serial number dates to the late 20s, and the bell on the trumpet, a model 43, was made in Elkhart, IN., and Bach didn't move there until 1965. Clearly something's amiss, but I can't tell if the serial number is fake, or the bell was replaced at some point, etc. Can somebody tell me what else to look at to determine the true history of this instrument?

I think you have a very valuable instument there. It is not uncommon for musicians to change the trumpet head. Who knows the reason why it was damaged. I still think you have a vauable instrument. I suppose you have already done everything online that you can. That's what I would do. If not, take it to a collector. They are amazing at this things.

37 vs 43 specifically.

Standard Bach Stradivarius bell models are 37, 43, and 72. The numbering system refers to the bell flare and rate of taper from the bell tail to the bell. The larger the taper, the more spread/diffused the sound will be.

The 37 bell (slower taper) provides a rich, focused sound, with good projection. It is the standard bell on the ML bore Strad. The 43 bell (faster taper than 37) yields a broader and brighter sound, more open blow than the 37. It is the standard bell on the XL bore Strad. The 72 bell (faster taper than the 43) has a strong, powerful sound that is darker than the Bach 37 bell. It is standard on the Bach Strad Vindabona model.

I won the bid for a "Bach Trumpet Mouthpiece" and was sent a trombone mouthpiece that had a damaged stem...I contacted the seller who wants me to return the damaged merchantise for a refund and I think he should send me the right mouthpiece...I wouldn't mind sending back the mouthpiece if it were usuable but would he try to sell it to some onther buyer? He claims that he doesn't know the difference between a trumpet and a trombone mouthpiece and that I should have known it was a trombone mouthpiece from the picture and was sorry for the inconvienience..He doesn't address the fact that the stem was damaged...

Yes, send it back. But also, rate him as a bad seller and report him to eBay for selling damaged merchandise, but only after you do the refund. This might prevent others from buying from that seller. Good luck, and sorry!