There had been earlier units built by Clyde.
>GM class = General Motors
Technically the GM1 was the F class and the early GM12s were the L class.
>After the CL the L came to mean Loco so we have AL, BL, DL, EL. Then
>marketing got the upper hand and the AN (Australian National) class was
>born.
I was once told L refers to the horsepower. The AN was the first 4000hp
loco, and as M was already taken they moved on to N. Going back to less
powerful units, K comes before L. Actually I think it was in the article
about the AN in AMRM last year.
Cheers
David