Yep, it is normal for the USMC vehicles to not have much in the way of markings...
I've got info from the USMC manual on vehicle markings on my website...
A lot of the marking standards have their genesis in WWII... Army in Europe put a lot of white paint (stripes, circles, stars) and unit numbers (lots of different units in the same general area) in order to help folks in the air identify friendly vehicles and for folks on the ground to figure out who was who and what belong to whom.. . USMC in the Pacific didn't have to worry so much about figuring out who was who since they didn't have as many units in a giien area, didn't have the air superiorty to be able to afford to be that visible from the sky and wanted to limit visbility of the vehicles more from the ground as well...
Of course, having said the above, there are a lot of USMC rigs that sported "unoficial" markings as well, nose art is still alive and well in the Corps and was plentify on tracks and trucks in Vietham (and is alive and well on equipement in Iraq currently....).
