Duramax 6.6L review - Transmissions

Janet L.

New Member
You only mention the Allison 6-speed (and 10 speed) transmission in connection with the Duramax engine.
I have a 2008 Thomas 4-window short bus built on a 2007 Chevrolet Express 3500 chassis, GVWR 12,300#.
It came with an LMM Duramax 6.6L and a GM 4L85-E four speed transmission and a 3.73:1 axle.
So at least occasionally they used a 4L85-E.
I was lucky to find one so new, the maintenance guy at First Student said they were expecting to keep it a couple more years, so I got it with only 140K-odd miles and fully up-to-snuff, but corporate sent them a batch of new busses, so this one became my Bus Named Sue.
Now to get on with finishing it.


Livin Life in the Right Lane
Staff member
Awesome! I'll get this one added to the article for other readers to know that the 4L85-E was paired up with the 6.6 Duramax in some buses. Thanks for informing us on this!