I have a Purple NOS BpBp horn p. #2926233 with a date stamp of 3428 is this the 342nd day of 1968 then. Thanks in advance.

It sounds about right, but

3428 - 342nd day of '68 = Saturday, December 7, 1968
or
3428 - 342nd day of '78 = Friday, December 8, 1978
or
3428 - 342nd day of '88 = Wednesday, December 7, 1988
etc.

You will have to confirm what format was used in '68 vs. '78 etc.

Dan Thank you very much for that information. Hopefully they were working overtime that week in '68 I didn't know if the newer issue ones were dated as I have 7-8 of them and most have no date code on them....

This won't make it easier, but I had the opportunity to check out a "survivor type" 99 "Omaha orange" RR a few months ago. Here's the horn black & odd fastener holding it to the core support.

The car was LA built & scheduled for Thursday 11/14/68, the date on the horn is "428" 42nd week of '68, ~ 3rd week (14th - 20th) of October. Is it original to the car, or replaced in '78, '88 etc.?

Dan that is messed up how it's attached. That bolt is going through the horn the wrong way,there must be a nut or clip on the other side of the radiator yoke since the threads are on the horn bracket....
I am thinking that's a "real" '68 horn and mine maybe a 78 or newer. The font on mine is bigger.