Well I have good news and bad news.
Bad news: you can't buy original Colt 2nd Generation parts as the company does not exist anymore, at least not the black powder revolver producing part of the company.
Good news: Uberti parts WILL work for most Colt 2nd generation revolvers. The Colt 2nd generations still had their parts rough cast in Italy and shipped to the US for production and finishing. I have a 2nd generation 1860 Army with the fluted cylinder but I use an Uberti engraved cylinder instead of messing up and dinging up the fluted one. Fits and works perfectly. Any of the other inside springs, hand assembly, bolt etc by Uberti will all work even though they may need a bit of hand fitting.