The Harmonic Balancer on my 1965 K-code car (San Jose/2.16.1965) has a stamp that reads "K5" (see picture). My first thought was this is a date stamp with K5 standing for October 5, 1965. However, that would mean the balancer is not original to the car's VIN-stamped K engine block which bears a date stamp of 5B5 (February 5, 1965). That is possible, of course, but I decided to do some research and turned to Tony Gregory's book on HiPo Mustangs. On page 8 and 9 he discusses these balancers, but never refers to a date stamp. He does, however, refer to "K" balancers, which leads me to think that might be what the K in K5 is referring to, i.e., the K is there to I.D. the balancer as one that fits a K-code motor (could the 5 be the shift, or the tech who stamped it?). The only other thing I noted on the balancer was the casting on the front that reads: C50E-A. I didn't mean to be so long winded, but if anyone can shed light on the K5 stamp, I would appreciate it. Thanks, Ron