The KE30 2 doors were available at the beginning of the 3rd generation, 1974. I also assume that they first came out as 2 doors only, then 4 doors were introduced in 1975. They both would have been available at the same time but only for a short while, 1975. We usually only got the 2 doors in previous models, so they must have changed their mind some where down the line and released the 4 door sedan.
Sadly I haven't seen many KE35's or seen their vin numbers to be able to tell when abouts they started. I assume it may have been around the same time as the 4 door sedans.
If you check out my database thread you will see the proof from other members cars and their vin numbers. (Link in signature)