Selmer's website has a comprehensive list of years versus serial numbers. You can check it out yourself at the link below this box.
But your's falls between 1947 and 48
The Selmer Trumpet with serial number 48697 was manufactured in 1970, according to the list in below register.
http://rouses.net/trumpet/selmer.htm
What year is a Selmer slikver trumpet have with the serial number of G21452 made? And does it have any value it has three mouthpieces
70453
Best estimates put this trumpet as being manufactured after 1998.
Best estimates put this trumpet as being manufactured around 1958-1959.
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.
According to Selmer's website 1952
It's difficult to be accurate as Buescher were taken over by Selmer in this period but its around 1975-1980.
1952
1894
Best estimates put this trumpet as being manufactured after 1984.
Best estimates put this trumpet as being manufactured after 1983.
Around 1963.
Most likely 1970.
Best estimates put this trumpet as being manufactured around 1952-1953.
Best estimates put this trumpet as being manufactured around 1947-1948.
Best estimates put this trumpet as being manufactured around 1951-1952.
Best estimates put this trumpet as being manufactured around 1950-1951.
Best estimates put this trumpet as being manufactured around 1951-1952.
Best estimates put this trumpet as being manufactured around 1956-1957.