You've got an early one alright. Your slide and frame were cut down from full size 1911 parts and welded back together in Combat Master size. You're barrel should be a two piece also (unless the gun was returned at some time and had it's barrel replaced). You might want to "carry it much and shoot it little" since a lot of the early ones didn't have the longevity of the later "one piece" slides and frames (and barrels). S/N's began at 2001, so you can figure out your lineage from there.
...Deeton