1964-65 Wheel Code ?'s
 

I'm looking for info on wheel date codes for '64-'65 but mainly would like to know when the "65" started to appear on the front center section next to the lug holes. Does that 65 really mean 1965, model year 1965 or is it a code that just happens to coincide with the year? I have a set of four I believe to be original to a '64 but they have GM & 65 on the center and no manufacturer marking or wheel size on the inside. Another pair I have does not have the 65 but has inside stampings of Electrofuse 14x5 J with a small 5 inside of a C and #799. Thanks for any help.

Paul