A Selmer Trumpet with a serial number of 43417 was made in 1950, so as of 2013 it is 63 years old. All Selmer trumpets have a serial number and there is a chart that shows what year the trumpet was made.
The date of manufacture for the Selmer Soloist B-Flat Trumpet, with a serial number of 43417, is not listed online. It is best to call the manufacturer directly or consult a music instrument store in your local area.