As said above, you need to decide on an era for period correct, as in yellow letters on a 3-colour camo deuce would be inaccurate.
For anything mid-1970s to present (ie post overall green), Sandcobra's examples are what you would go by. Note that the Marines are somewhat notorious for putting the markings in non-standard places, so what I write below is a guideline only, it is the standard for that period, and what I have found to be the most common.
For a deuce (or 5-ton)-
the USMC goes on the front bumper and on the rear of the bed on the
driver side.
The vehicle's 6-digit serial number (during this period, they always have 6 numbers, no letters) goes on the
passenger side.
USMC and the 6-digit number go on the sides of the hood, close to the rear edge.
The unit designator, which apparently few outside the Marines can interpret, will be an M followed by 5 numbers. Best I can tell, the first number is the Marine division the unit is attached to, so 1 for West coast, 2 for East coast, and 3 for Okinawa. An example would be M21401.
On a deuce, this is normally centered on both doors and somewhere in the middle of the tailgate. It is sometimes also on the front bumper, passenger side.
All the above is done in 2" high stencils. Colours are black on tan, brown or green areas, green on black areas. If the lettering crosses a camo line, the colours will change as appropriate, to the extent that parts of one number/letter may be in different colours.
The Marines do NOT use the tan rectangles to put there markings on like the Army does.
Note the style of the M in USMC. It is best visible on the side of the green toolbox in Sandcobra's pictures. It is not your usual stencil M. My son, who drives trucks in the Marines currently, says the USMC comes as a pre-cut stencil with that style M on it. The regular stencil M is sometimes used on repaints, or on the later trucks.
Later trucks, such as MTVR and the LVS/LVSR, do not conform to what I have said above.
Clear as mud??
Note that after WWII, the USMC is always presented that way, never U.S.M.C.
The attached pictures are all of 5-ton M813, just because that's what I have most of, but the deuce is very similar and marked the same way.
The truck in pics 1 and 2 is on Camp LeJeune, 2nd MarDiv. Pic 3 is in Bosnia, belongs to 1st MarDiv. (Pic 4 is in my pasture!). My own M813 came off LeJeune and is marked exactly the same way.
Cheers.
