What car is it going on ?
I've just had a load of 4 into 1 manifolds made for Pre-Crossflow and Crossflow's in Anglias...
But the shocker was they also fit perfectly onto MkII Cortinas.....
So I suspect they will also fit onto MkI 'tinas & Corsairs.....
Jon Hill the Classic Ford photographer has one on his MkII Cortina.....
The manifold is 22" primaries that are 1.5" in diameter and has a 2" pipe exiting the collector.
Let me know...