Please see the picture of the dated spark plug wire set I just received. As you can see, the wires use a script of one hyphen format of 1Q - 69. I contacted the vendor that I had purchased these from, they say they contacted the plug wire manufacturer who said that the format of the script that is printed on the wires is correct and accurate reproduction of what was used by the factory at that time.
The vendor also said that Corvette parts suppliers are the biggest buyer of these dated plug wires from the plug wire manufacturer, and that the Corvette parts suppliers will have it no other way than the one hyphen format script.
Perhaps someone with a good deal of experience with authentic C3 Corvettes as they came from the factory can offer input as to what the factory in Bowling Green used at that time.
However, my informal research on the internet of several other retail vendors of these dated spark plug wires show that they all use the two hyphen format
( 1 - Q - 69 ) in their product description and also in their related charts that show which date coded plug wires to order for various VIN number ranges and/or vehicle build dates. Pictures of their plug wire sets show the two hyphen format.
I would like to use wires that are printed with date code format that is a correct and accurate reproduction of what would have been found on a Camaro leaving the factory back in 1969.