The were 88 locomotives spread over 8 orders during the course of 4 years. It's logical that somewhere during that time the specs were revised to change the throttle.
If I were to hazard to guess, I would say the external throttle linkage began with the 9015 of the 1928 production.
The drawings in the MR Cyclopedia mentioned earlier are of the 9017, which was part of the 1928 production. 9000-9014 were built in 1926.
However, it's obvious the the 9000 never had external throttle linkage.
Rusty
