Wow - I'm looking at the Back Loyalist Mouthpiece guide:
BachLoyalist.com - Mouthpiece Models (Trumpets)
and learning a bit. The different options are remarkable!
Looking at the Buescher - it is marked True Tone, s/n 332544, with LP and 257 stamped on the bottom of valve #2.
There is a good bit of denting in the rear of the bell section - next to the mpce, and some smaller ones elsewhere. The bottom springs are different - our other horns are Olds Ambassadors (2 trumpets, a cornet on the way), and a Reynolds Medalist in pretty nice shape.
This horn sounds quite good - considering I paid $2.50 + $25.00 for shipping. Even has a great case!
The added high register I got from the 99-D has me thinking about a similar trumpet mpce. A lot to study, and more to try!
Bill