That should work pretty well as long as you have some place on your truck with lots of metal; antennas like this one depend on that to work properly. However, if all you're interested in is MARCS, a cell phone antenna will work very well for that application. There are so many models out there for this app- in fact even a window mount would likely work very well, as long as you don't have any metallic tinting, which can seriously detune it.
Best regards..Mike