Plastic air horn ID

[john walker's workshop]

I need a refresher on what year and model these plastic air horns originally came on. The yellow one on the left has a 39mm bore, the others are 46mm.

[digitaldgp]

Hi John,

My 1970 911T had the the black plastic horns mounted on Zenith carbs. Hope this helps.
I had them replaced by Al at X-Faktory with metal ones.

Dave

[proporsche]

Hi John, i just did 1971 911S and it has the yellow type

Ivan

[john walker's workshop]

But these yellow ones are smaller ID than the MFI or carb tops.?? Got a bunch of various colors and don't remember what they were on. Light gray, dark gray, black.

[harvardma]

Light gray 46mm is what I have on some 911S MFI stacks