Yea, I was thinking the Allison 1000 would be the way to go (although there are a couple other brands offer the same gear ratios)
The new 2.8L Cummins are showing higher RPM curves than the previous BT's
The 4-6BT's are just too high on the noise scale for the client.
He's comparing everything to his brand new Chevy/GMC diesel pickups.

Moparguy, that Isuzu site is gone.