Occasionally I see old American Jeeps around town. As far as I can tell, they're driven by cops or soldiers. They've been restored immaculately, with new paint jobs and new stenciling. Here's one I snapped parked on Suong Nguyet Anh one Friday afternoon.
Note the yellow stenciling on the front bumper that reads "America" and "USMC." Also note the word "Army" on the passenger side. I don't know if this vehicle originally was owned by the US Marine Corps, but I'm pretty sure USMC vehicles didn't have the words "America" or "Army" on them.
Several museums in Saigon showcase captured American-made equipment such as helicopters, planes and tanks. All have US military markings instead of the former Republic of Vietnam markings. I find this odd, because by the time Saigon fell was liberated in April 1975, the American military presence had been reduced to a relatively small number of advisers and security personnel. Most equipment left behind was transferred to Southern forces and repainted by their new owners. I would expect a lot of the equipment on display to have the old Southern military markings.
So what explains the preponderance of not-quite-accurate US military markings on the captured equipment? My guess for the first reason is pride. The Vietnamese government derives no small measure of its legitimacy from the fact that it beat back the American imperialists and their puppets to liberate the South Vietnamese people, thereby ushering in an unprecedented era of freedom and prosperity under a one-party system of government. Displaying instruments of war ostensibly captured directly from the American military makes a more powerful trophy than anything captured from the South military.
My guess for the second reason is the authorities are loathe to display any yellow and red symbols of the former Republic of Vietnam. Public display of such symbols may stir memories and cause trouble.
So it makes pretty good sense to me that they would repaint all captured equipment with US markings. If I were them I'd do the same thing.