from King serial numbers list on Brass History website:

https://tinyurl.com/dzsc7ukh

from «0» in 1894 the numbers reach «100000» in 1914

1914—1986 6-digit numbers, reaching «999999» in 1986

1986—1995 6-digits prefixed with 2-digits (year minus 50, e.g. «36 156789» =’86 = 36+50)

1995—2001 6-digits prefixed with «5»

2002—2024 6 digits, from «100000» in 2002 and upwards

My King 2B silver sonic with f trigger only has two numbers on it? One underneath the trigger rotor ‘943’ and one on the main tuning slide ‘939’ are these the serial numbers? If so what year is it please?

[quote="Johnskneehurts"]My King 2B silver sonic with f trigger only has two numbers on it? One underneath the trigger rotor ‘943’ and one on the main tuning slide ‘939’ are these the serial numbers? If so what year is it please?[/quote]

Those are NOT serial numbers. Do you have a Symphony 2B (which is really an older 5B)? If so, it has to be at least 60 years old. It's possible that over the years someone has replaced the part that had the serial number. Most King serial numbers are either on the receiver for the slide tenon, or on the cork barrel near the tenon. Older instruments may have additional numbers on the water key lever or the outer slide near the brace. I played a Silvertone 2B (small bore) from 1947 that had serial numbers in 5 different places (they all matched).