Mack Trucks, Inc. (Mack) is recalling certain model year 2015 GU trucks manufactured April 28, 2014, to June 19, 2014. The Cummins ISL engines in these vehicles may have been equipped with Fleetguard UFF-XT fuel filters, part number FF63009, whose filter shell may separate from the fuel filter nut plate causing the engine to stall without warning.