i have a truck model breakdown guide for several models and for komatsu trucks it describes the following:

First letter designates: F = Forklift
Second letter designates power plant: G = Gasoline, D = Diesel, B = Battery
Third and fourth digits combined designates capacity: usually 2 numbers, 50 = 50/11,000 (metric tons/Pounds).
Fifth and sixth digits combined designates truck specification: usually 2 letters, A = not defined, T = Torque Flow Transmission
Digit after dash designates Type number

So the big question is what the "A" stands for, the chart i have is several years old so it may have been updated since it's creation, i'm sure komatsu has made changes over the years to incorporate new designs or options with their machines so what i would suggest is to consult with a komatsu dealership and ask them to decode the model number for you.