Sanders McNew
Rolleiflex User
2.8E3 means it's the third version of the 2.8E. The 2.8E had a fixed hood and a glass focusing screen, the 2.8E2 had a removable hood and interchangeable screen. As for the E3 I'm not sure.
The E3 was the same as the E2, except it did not have
the E2's integral light meter.