carb velocity stacks ? help ID

[typ901]

all;
I ran a search, but came up empty. pictured here are 2 metal carb velocity stacks (hopefully that's the right terminology)
the differences are;
unit on the left has a thin mounting flange w/ 41MM bottom opening.
unit on the right has a thick mounting flange w/ 46MM bottom opening.
what have I got ?
TIA
jerry

[1QuickS]

All air horns for Weber triple throat carbs have 46mm bottom diameter. Heights are either 50mm or 56mm. Earlier horns are spun from 2mm thick sheet and their bottom flanges are 2mm thick. Later ones have thinner flanges and some are of brazed construction joining the bottom flange to the horn. Also, there were plastic horns in either grey or black. Your horn on the right is an early, spun, 50mm tall horn and the horn on the left is for some other application.

[typ901]

thanks Paul;
greatly appreciated!
could the other stacks be Zenith type ? I can't imagine what else (in my pile of junque) they would have come on.
thanks again
jerry

[1QuickS]

Hi Jerry,

Zenith 40TIN and Weber IDA3C all have 46mm diameters for the air horns at their base.

MFI air horns for 911E for 1969 through 1971 have 38mm diameter. MFI air horns for 911S have 46mm diameter for 1969 and 42mm diameter for 1970 through 1971.

Stud spacing for MFI horns is 66mm for 1969 and 72mm for 1970 through 1971.

1972 and later MFI systems did not use individual air horns.

Possibly a horn for a four cylinder carb?