I used to own an Uberti made Colt 1860 Army from 1967 with "A" prefix.
Regarding the 5 models of Belgian Centaures, the
# Regular New Model Armies (RNMAs: 8" barrel, 3-screw frame with notches in the recoil shield),
# 1st Variation Marshal Models (5,5" barrel, 3-screw frame, stainless look),
# Pocket Army Models (4" barrel without loading lever, 3-screw frame with "round" recoil shield)
don't have a prefix.
# Civilian Models (8" barrel, 3-screw frame with "round" recoil shield, silver plated TG and BS) have the "C" prefix
# 4-screw frame models: Cavalry Models (7,5" & 8" barrels) and 2nd Variation Marshal Models (5,5" barrel, fluted cylinder, stainless look) have the "F" prefix.
Long Johns Wolf