From Second Ed Colt DOM book:
1860 Army Model 11835 made 1978-1984, S/N range 201000-212835. And
1860 Army Model 1994-2002 by Colt Black Powder Arms Co. S/N range not stated - these are, i think, the "Signature models".
Blue book has a Black Powder book that contains a lot more information, and i think more S/N information. It covers not only Colt but many other BP reproductions and modern BP guns. And has pricing data....