In searching for 'date coded GM Hurst shifters', I found the following reference from 3/24/05 on the Supercar Registry: (from hotrodpaul...
"I need help with the datecode on my 69 Camaro SS 396 Hurst Shifter. It looks to be original with the 3138 number stamped on the side, rubber molded inserts where the rods attach, Chrome round shift handle, etc. The date code reads "39D12K" and the car was assembled in late April. I assume the 9 means 1969, D is April, and 12 is the 12th day, but what does the "3" and "K" mean? I can post pics if needed."
Using the decode schema provided by PaceMe (Steve S) ie. "MmYxxxxx", hotrodPaul's codes translate to: March, 69.. which is again consistent with the build date of the car (April car, March shifter).
So far, the examples that have been posted are consistent with his schema....