The SN is probably GCA1275. It is one of the 94 Giuseppe Garibaldi freak dragoons that were made without the gold etching on the barrel and cylinder. The barrel and cylinder are in the white - not nickel plated. NIB value is around $800.
Fingers (Show Me MO smoke) McGee - AKA Man of Many Colts - Alter ego of Diabolical Ken; SASS Regulator 28564-L-TG; Rangemaster and stage writer extraordinaire; Frontiersman, Pistoleer, NRA Endowment Life, NMLRA, SAF, CCRKBA, STORM 327, SV115; Charter member, Central Ozarks Western Shooters
Cynic: A blackguard whose faulty vision see things as they are, not as they should be. Ambrose Bierce