From the outside
A Korean-made CoCo 2 can be most easily identified from the outside by the channel select switch beside the TV output and a horizontally mounted modulator (metal box) which can easily be seen through the top grille, to the left of center.
Because it is also possible that these systems with the horizontally mounted (flat) RF modulator can have a the newer 6847T1 (typically marked XC80652P), it is necessary to either peek through the grille to see the markings on the large 40-pin chip next to the RF can to make sure it reads MC6847P, or to connect it to a TV such that you can examine the letter 'O' or number '0', or both.
On a 6847, the letter 'O' will be rectangular and the number '0' (zero) will have no slash through it:
On a 6847T1, the letter 'O' will be more round and the number '0' (zero) will have a slash through it, as shown below:
From the inside
If you are able to open your CoCo 2, it is possible to confirm the board was manufactured in Korea by looking for the horizontally mounted RF can on the top left of the board. The 6847 (which should be marked MC6847P) should be the large 40-pin chip near the RF modulator. (If this chip is marked XC80652P, then it is a 6847T1.) Note that there are a few Korean CoCo 2 board layouts. 2 examples are pictured here. Note that some 6847s may be soldered to the board while in other systems they are socketed.