Date: 1959. Owner unknown
This is a C trumpet, which means that a C on this instrument is a concert-C, and not a concert-Bb as is the case on a Bb trumpet. The easiest way to tell is the fact that the main tuning slide doesn't extend as far towards the bell as it does on a Bb instrument. By the looks of this and some other pictures, I would say it has bottom spring valves. The trigger on the first slide is original. It is interesting that the styling of this instrument is taken from the 1955-1957 6B Victor: bottom spring valves, no coprion leadpipe. Might this be an indication that the later version 6B was an attempt to make a trumpet more similar to the popular 38B Connstellation while the older design was at least as good if not better? Except for the trigger, the same can be said for the 35B Victor D trumpet and the 2A Victor Eb cornet. Please see Comparative quality of Conn instruments, part 2 for a longer discussion of this.
This instrument has a serial number dating to 1959. The case is also of late 1950's vintage and is entirely consistent with the instrument and its serial number. Both the case and the instrument are clearly by Conn. However the model number list gives this instrument with a start date of 1961. I understand there was (is) a brochure "16 New Sounds for 1962" which included the 25B. My theory is that this 1959 model might have been a pre-production test instrument. There are several more examples of this situation where there is a model with a serial number pre-dating the first year of production according to available publications, such as the 34B Alto trumpet or the 36B Lightweight Connstellation. It would therefore appear that the person ending up as the owner of this instrument after it was sold on eBay is a very lucky person. The end date of 1969 is a guesstimate; it does appear in the 1966 catalog but isn't mentioned in an early 1970's catalog.