Feb,1969 plant GAD....according to chart. Check on the Mustang forums ( Shelby) Lots of info(links) on some threads there. Dig deep enough and you'll find what you are looking for.Started with a guy wanting to verify the spare he had in the trunk. Unless pure coincidence, the numbers on my tires (5) coincide with the chart and translate to the proper time frame ( build date). Sorry can't be more help Bryan ,one of many numbers, and not a lot about it. Did my reading last year around this time, found what I was looking for and moved on. Shame about the tires, they were severely abused(hole shots) very early in the history of the car and used solely for winter storage. Most likely were off the car by 69. Side walls show no dry rot. In 90 I wanted to put the Ralleys back on and had new tires mounted, decided to keep them.