This mod emulates the Buick Dynaflow.
The real car has two gears, with one normally in use Drive and Low available for acceleration.
On BeamNG I can't have these two gears on the transmission because when you are at standstill it will always be in first gear, no matter what shift points (same thing for in manual mode). And putting the ratios the other way round didn't work either.
So instead, the transmission has one gear, and a rangebox. Hi-Range is equivalent to the real car in Drive, and Lo-Range is equivalent to the real car in Low mode.
I also have two torque converters simulated. The original, being able to multiply torque by 2.25x and the triple turbine being able to multiply to 3.
in real life the triple turbine achieves this by switching stator pitch when you floor it (causing RPMs to jump a bit) but I can't simulate this in BeamNG (without an adventure into LUA). So I just increased the torque at stall point.
The torque converter sizes are set so at stall it's around 2700RPM