There are several dates to look at. The casting dates in the front and rear cases are cast into a wheel shaped circle divided into 12 pie shaped segements. In the center of the circle will be a 2 digit year (example 69 = 1969) These segments are either empty or have any number of raised bumps in them (actual bump count does not matter). The segments that have raised bumps denote a month marked off of the 12 month calender, for instance if there are 3 remaining empty segments (marked in blue) then the casting was done sometime in September of that year, in the case shown below it decodes as September of 1969. The front and rear dates usually matched but not always, seeing them a month or so different is not unusual.