Was the shires dual bore sold without the engraving on the cap? I have one that is supposed to be a dual-bore but the cap isn't engraved. I also have a std shires rotor with no engraving. They are different. The "dual bore" has a gold cap and the std rotor has a silver cap. The "dual bore" foremost tube coming out the top goes up higher before rounding over toward the back of the horn. Any info on this or maybe a date if it is indeed factory?

I believe some early Shires dual bore rotor caps didn't have engraving yet. I'm not certain about that, but I'm pretty sure I saw dual bore prototypes and early production valves without it. I'm not enough of a Shires expert to know when the first valves were rolled out but someone else on the forum may know. Could always be a custom job too if the wrap is a little different.

I have an early dual bore with a silver cap that also lacks the engraving. They probably started the engraving because the two valves do look fairly similar. I think they played around with the wrap for their prototype and early versions as well.