Transmission Truths
The Allison transmission has just as many speeds as the manual. Plus, it has higher overdrive gear ratios. The double-overdrive feature allows the Duramax to loaf along-even at highway speeds.
Model
ZF S6-650 (ML6)
Allison 1000 (MW7)
Type
6-speed manual
6-speed automatic
| Gear Ratios |
| 1st | 5.79 | 3.10 |
| 2nd | 3.31 | 1.81 |
| 3rd | 2.10 | 1.41 |
| 4th | 1.31 | 1.00 |
| 5th | 1.00 | 0.71 |
| 6th | 0.76 | 0.61 |
| Reverse | 5.23 | 4.49 |
| Rear Axle | 3.73 | 3.73 |