Remember that a potentiometer could have been replaced so it is always best to look at a few of them.
Later potentiomters used a two digit year code making the number seven digits long.
In this case the fourth and fifth digits are the year and the sixth and seventh digits are the week of manufacture.
My discussed pot in this thread is R137yyww = R1378131 = 1981/31st week (R137 = mfg)Typically, before 1981, you will see "wwyd" = week/year/day of week Example on a 1970s Stratocaster neck butt date "0903-2455" 09=Stratocaster 03=Maple Neck 24=24th Week 5=1975 5=Friday What I've been understanding, serial numbers are only an indication of a year, but could be five years off, like my Telecaster.
The neck-butt stamp will provide year/week/day or year/week. The year is a big thing to some for parts and is the seller telling the truth. To find the year of my Strat you need to pull off the neck. Gfs sells them in the proper range for each place Neck, Middle and Bridge. I will end up with two types of Telecasters and two types of Stratocasters.
When I replace pick ups I put a new set of pots on it. I do an install that is cleaner than the ones that came new on the guitar.