[_Graf_]

Well you really can't tell 100% of the time between the E-1,-3, and -4. E-1s differ in that they do not have the MF/FF cannon in the wings. E-3s did have the nose 20mm but no external difference from the E-4.

Now the new "squared" off canopy was introduced on the E-4 but many E-1s and E-3s received the new canopies as well. So...