The early 30274 9mm and 28926 .40 ejectors didn't have numbers on them, but they are shaped like this:
The old 9mm ejector was stamped 336, the old .40 ejector was stamped 1882 and they both had this shape from a side view:
The old ejectors work fine, there's no need to replace them with the new ejectors unless you're experiencing ejection problems.
Gen4's with a test-fire date after 10/10/2011 will have the new ejectors. Gen3's still come with the old ejectors.