The canon history of the Metal Gear series and the history the Snatcher story is set in have several common elements, such as the TX-55, and Dr. Pettrovich, who developed it, but it should be noted that they are basically two different worlds. (Metal Gear Solid makes it clear that the catastrophic biohazard outbreak that occurs during the 90s in the history of the Snatcher does not occur in the world of the Metal Gear series.)
In Metal Gear Solid 4: Guns Of The Patriots, a non-AI "Metal Gear Mk. II" and "Mk. III" as created by Otacon make an appearance, but these radio controlled machines were intended as an homage to Kojima Hideo, the game director of Snatcher and the original Metal Gear. Other than an homage, they are not connected to the above mentioned robot in any way.
