Without looking at any info there was the 70-100-71-102-122-73-104-124-106-126-108-128-800-1200-582.
I'm sure I'm missing some, but IH had several gear drives in each series of Cub Cadet line pretty much to the end.
Chris
I belive Tom answered you realy well.
Im curious what your asking exactly??Your profile says you have a 70 and 100,both gear drives made after the original!!
The 1535 (cyclops series) was the last gear drive garden tractor the use the Cub style 3 speed transmission (but with an aluminum housing). I don't know what year it was discontinued (probably 1991 or 1992, but it began production in 1990. The cyclops series ended in 1997 so it was definetly before that.