I have a NV4500 in my 59 GMC 1/2 ton longbed with 3.70 rear gears. The OD ratio is 0.73:1 or a 27% od. The MY6 is a 4 speed, 1-4 match up pretty close to 2-5 on the NV4500. The NV4500 offers a 5.61:1 granny gear.

Both are excellant transmissions that are up to the task of a 3/4 ton pickup.

What engine are you running?