Test Drive: Navistar Prostar+ with Cummins ISX
The switchback aftertreatment package is trucked beneath the passenger door, close to the turbocharger to maintain high exhaust temperatures at the catalyst.
The cockpit is familiar territory, except for the DEF tank level gauge.
Cummins and Navistar Reunite
An easy fit; the pre- and post-2010 ISX aren't much different externally.
The 23-gallon DEF tank sits on the left-hand side between the battery box and the fuel tank.