Looks like a solid build. Not too bad with the airbrush work either. Fine lines can be difficult to acheive. One comment though, MERDC has 4 colors, not 3. There were 2 types of Desert MERDC, Red Desert and Gray Desert. Red Desert MERDC (as it looks like you are replicating) is made up of Earth Red, Earth Yellow, Sand, and Black. The sand should also be in smaller squiggles like the black.
Check
here for more info.
Here is an M577A2 in Red Desert MERDC.
M60A3 pattern (basically the same as the M48A5 pattern) is here.
More views
here.Good job so far. If you add the sand squiggles, it will look great.