I agree with just about everything said above, except this:
There are no other Colt autos that use "Mark" as part of the model identification.
Colt made a .38 Special pistol, along the lines of a Gold Cup, called the Mk. III. It was kind of a weird gun, with a delayed-blowback action, even though there were lots of .38 Special conversions around that still used the swinging link, and I don't think it was ever very popular. Of course, one has to wonder which guns were considered Mks. I and II?