Antique Silvertone guitars were manufactured by five guitar makers, Danelectro, Harmony, National, Kay, and Teisco, to be sold by Sears department store from the 1950s into the early 1970s. While all of these guitars bear the name "Silvertone" on their headstocks, the design of the instruments differs greatly from manufacturer to manufacturer. Many different models of Silvertone guitars exist, but the vast majority of them can be dated via the serial number. In general, the older the guitar is, the more it is worth.
Search the guitar for a serial number. Look behind the headstock and on the base of the neck. If there is a four-digit serial number, which the vast majority of Silvertone instruments have, you can use it to find the guitar's age.
Remove the guitar's neck if you cannot find the serial number anywhere else. Most vintage Silvertone guitars have the serial number stamped on the neck pocket, which is the piece of the neck that hugs the body of the guitar. Remove the strings and unscrew the screws at the base of the neck. Carefully separate the neck from the body of the guitar. Look for the serial number in the neck pocket.
Read the serial number. The first two digits indicate what week of the year the guitar was made, and the last two digits indicate the year the instrument was made.
Take the guitar to a guitar shop, preferably one that sells vintage guitars, and inquire about dating the instrument if you can't find a serial number.
A small number of Silvertone guitars have the necks glued to the body of the guitar. Glued-on necks must be removed with heat, usually steam. Do not attempt to remove a glued neck unless you have significant experience doing so. It is extremely easy to damage the instrument if not experienced. A few Silvertone guitars have a three-digit serial number in which the first number is the last digit of the year, and the last two digits indicate the week.