Impossible to value a weapon based on just the serial number
1948
The Smith & Wesson 14-5 was manufactured between 1991 and 1999. Value will depend on conditon.
50-450 usd
No such model number in S&W.
50-500 usd
K 7981 smith&wesson
Anywhere from $300 to $550.
1970
100-500 USD
WHATEVER SOME BUYS IT FOR
Standard Catalog of Smith and Wesson Firearms by Supica and Nahas History of Smith and Wesson by Jinks.
The Smith and Wesson K frame revolvers were made from 1946-1983.