I've looked on the Tuff Torque site and through the Deere parts catalogue but remain puzzled on the trans specs.

The X300/320/340 tractors use a Tuff Torq K46 or a derivative there of. Rated for 131 to 171 ft lb torque and 675lbs axle weight max. Powdered metal gears.

The 19.5HP LA110 and 21HP LA120 uses a hydrostatic trans with a Deere part number of AM134582.

The 21HP LA130,23HP LA140,26HP LA150 use the M1A10911?

The LA tractors are using a “cheaper” dry disk brake trans than the internal wet brake K46 ? It looks like a K55? The Tuff Torq site lists their K46 as their lightest duty trans and post no specs on a K55 but they do show a parts diagram etc for the K55. Does anybody know what axle torque, axle dia and weight capacity a K51 or K55 is rated for? Or for that matter what transmission(s) Deere is actually using in the LA line of lawn tractors?

LA 120 uses the T40.
Although the T40 has same physical appearance as the K46 transmission, it is has a different specification as a result of lighter internal hydrostatic & gear components.

The rated torque of each is as follows:
T40 - 130 ft lb.
K46 - 171 ft lb.

Regards,

Duane Deardorff
Engineer
Tuff Torq Corporation
5943 Commerce Blvd
Morristown, Tennessee 37814