All Danelectro, Silvertones, and Coral use basically the same serial number scheme, with some exceptions. But for the most part you can date your Danelectro from the serial number.
The usual serial number location is in the neck pocket. But occassionally you'll find it hidden on other parts of the body along with other random scribbling.
Most Dano serial numbers are 3 or 4 digits, and decode like this:
U-1 Serial Number
Serial number on neck butt of a 1960 model 3021 double cutaway shorthorn.