I have an 01 Dodge 4x4 with the auto, pulling my 33' Toyhauler to Glamis and back the tranny started slipping. Got a DTT tranny and all is well now
As for mileage it gets 16 around town, and from 18 to slightly over 20 on the highway. Has plenty of power to pull grades with the toyhauler, and I only have a 65HP Edge box. The motor is awesome, the chassis will fall apart long before the motor wears out.