I am not sure if the M48A3 was camouflaged in true MERDC camouflage scheme. That pattern of camouflage came around 1976 and would have taken a few years to fully implement. I know you can see various other armor of the time in locally camouflaged, but not in an official standardized paint scheme. For example, here is an M48A2C during gunery in Korea. It has a locally applied camouflage pattern, but not MERDC. It is probably safe to assume that a US Army M48A3 would be in OD green. Having said that, it is possible to see the M48A3 in what looks like a MERDC scheme in service with US allies. Countries like South Korea, Spain and Turkey used the M48A3 long after the US discontinued its use and many of our allies used MERDC-looking schemes on these tanks.
Further muddying the waters are photos of display tanks painted in current (for the time) schemes. For example, when I was stationed in Germany in the 1980s, the M4A1E8 and M24 in our area were both painted in current MERDC schemes using the same paints we used on the M60A3TTS tanks. Similar things probably happened to display M48A3s.
Now this is probably a USMC M48A3 in desert MERDC scheme, but it could also be the California National Guard.