Early 833 ID???

It's easy to check. Just put it in first (that's the rear shift-fork point on the side cover, and turn that clockwise). Then turn the input shaft until the output shaft has made one complete revolution, and count how many times you've had to turn the input shaft.
If that's little over 3 turns you've got the 3.09 first. If it has turned about 2,5 times it's the 2.66 first.

Antoon