Cast Plug-in CAMPAGNOLO dropouts?

[GetBornFree]

I just picked these up on a whim on eBay for my collection because I had never seen any before. Kind of bizarre - they are cast plug-in style dropouts, but stamped Brev. Campagnolo. I can't find them in any campy catalogs. Anyone have a guess to the era? Seller said 70s, but I doubt it...?

http://tinyurl.com/qc6cyev

 

[stringfellow1946]

They have the two holes for the Portacatenta. As far as I can find out the Portacatenta was introduced by Campagnolo in 1977 & faded out in 1983/4 so my guess is between those dates. Not very exact I know but its the best I can come up with, hope its of some help?