JRSpicer426:
Serial numbers in the 358xxx range shipped in December 1920, so I would place your friends gun in 1921.
Barrel lengths were 2, 4 5 & 6 inches, measured from the forcing cone to the muzzle. If you have a 6.5 inch barrel it was probably rebarreled at some point. As Oyeboten pointed out, the serial number will usually be stamped on the flat under the barrel. If it is a different number then it's not original. If there is a star stamped beside the serial number then it is a factory rework.
79708 is an assembly number used to track fitted parts in the factory - they had to be disassembled for bluing for example. It is irrelevant once the gun has shipped.
The .38 Military & Police Model of 1905 4th change was produced from 1915 to 1942, with roughly half a million made, so they are not exceptionally rare or valuable.
In 2006 the Standard Catalog of S&W gavew the following values:
ANIB $1200, Excellent+ $450, Excellent $335, Very Good $250, Good $200, Fair $135, Poor $75.
If it has a round butt, double the value, as S&W had transitioned to the square butt as standard for this model. If it has a factory nickel finish then the value is higher. If it has factory target sights the value is higher.