You're most welcome sir.
I don't have access to Colt's serials after 1978 right now but, I would bet your 1911 is of 1985 production. I have one from 1984 with the serial of SS0571X and one from 1987 at SS2884X.
If you call Colt at 1-800-962-2658, they will be happy to tell you it's DOB. :wink: