This Bach Stradivarius has a number 37 bell and medium-large bore.  It is the standard all-purpose instrument for college-bound players and, for this reason, it serves as my base of comparison for all other models.   It is of 1990's vintage.  Small dents have happened and you can see some areas where they have been removed, most notably a slight crease on one part of the bell (see the lower right-hand portion of the bell image below).  This instrument plays beautifully with smooth valves and slides.  I would take it on a gig without worry.