A good book on the 22 single actions was done by Don Wilkerson in 1993. It is still available. The information below came from his book. The G-Series revolvers were produced in 4 3/4", 4.4", 6", and 7 1/2" barrels between 1970 and 1977. The factory model number for the 6" dual cylinder Peacemaker was G-1461. Total production was reported as 190,830 G Series revolvers (Steel frame Peacemakers and New Frontier). Of that total, 90,637 were Peacemakers. The majority were packaged wtih the 22 and 22WMR cylinders. The 6" barrel variation had the highest production of 39,455. The New Frontier 6" had production of 43,983 revolvers with dual cylinders. Only 17 revolvers were assembled in 1977 and the highest production year was 1974 (55,007) with both the New Frontier and Peacemaker revolvers. Only 190 were produced in 1970.
The rarest of the Peacemakers was the 7.5" with only the 22 cylinder (1,666 production) and the same applies to the New Frontier model with 1,558 production with only the 22 cylinder.
The Peacemaker and New Frontier were discontinued when Colt decided to install a crossbolt safety feature. Advertisements showed both a Peacemaker and New Frontier models to be introducted with the crossbolt safety. But, only the New Frontier was re-introduced in 1982 and discontinued in 1986 (only 202 revolvers assembled that year). Nice revolver. Hope you enjoy it.