Gavin, the first style ejectors used the mainspring in the lock, the lifters and cocking rods to eject the spent shells. The forarm housing utilized the split ejector/s. These ejectors parts are non-existant now.. Years ago Skip Dunlap (RIP) had some made, and I was fortunate to get a pair for my 2E.
Also the for-end metal was a little wider than the second style ejctors that housed the springs instead of using the locks mainspring.
I have pictures but no dimensions