Some early examples of vintage Timex watches have a purple or black stamped code which can be found inside the case-back. When used in conjunction with dial codes these stamps are a great way of telling if your vintage Times is all original or has been cobbled together from random parts providing that the dial codes are present.

Case Back Numbers

Stamped NumberYear
91967
81959
71960
61961
51962
41963
31964
21965
11966
Vintage Timex Case-back Stamped Codes

Text Codes

Some case-backs also have other markings such as letters JTX, PAX and others stamped on the case back. It is assumed that these were either a production run, quality assessment, location or combination of these.

If anyone knows more then please let me know.