Gary,
What is it you actually need? Usually it's much easier (and cheaper) to rebuild what you have than get another gearbox. Like all Albions the E type comes iin top mount, bottom mount and pivot mounting. They are also made in a range of chain lines. Finding one identical to what you have ain't so simple plus you can more or less take it for granted that it will have the same wear as your present box.
I can lead you through a rebuild if you wish.
Cheers,