I'm about 2 years into my Mercedes diesel journey. My initial reaction was that the motor was always reving too high until I became accustomed to the "feel" of the vehicle.

Obviously if you're capable of this type of project you know to factor comparative tire height into the diff gearing.

While 2400 rpm's may be the most economical rpm, I'd suspect you would be down shifting on every grade if you set your differential to cruise at that ratio. I'd set it up to go 70 mph at apx 3150 rpms so it would be useable on an interstate if you ever need to drive there. This would have you at a comfortable 2700 rpms at 60 mph for your local roads you mentioned. This is about 15-20% higher rpm's than you might expect to set up a comparable gas motor and 30-40% higher than a DI diesel. But to me, this is just how these motors roll.

Even though your truck is lighter, I'd suspect the aerodynamics at 60+ mph would offset the weight gain compared to the donor vehicle. At lower speeds the lighter weight should be felt in the seat of the pants.

I'd definately can the slush box though and mate it up to an AX-15 5-speed (cheap adaptor plates available) if it were me in order to get the max out of the power plant.

By the way, your project is awesome!

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