According to the "Third Edition Blue Book of Modern Black Powder Values" by John Allen the first "Second Generation" guns Colt offered as the "C" series were introduced in 1971 (1851 Navy) and 1974 (Third Model Dragoon). Production continued thru 1976. They both were produced in the Colt factory using castings that were made in Italy.
The "C" series has a bright "Royal Blue" finish while the "F" series has a dark bluing typical of other Colt pistols. Like the originals, most but not all have the backstrap and trigger guard silver plated.
The C series 1851 was made in several different styles and editions, many with the square backed trigger guard and about 100 with the later model round trigger guard.
The serial numbers for the C series 1851's is 4201 to 25099.
The "F" series was made 1978 thru 1982, also at the Colt factory. As I mentioned, they have a dark blue finish.
The "F" series added the 1860 Army, 1861 Navy, 1862 Pocket Navy, 1862 Pocket Police, Walker, 1st Model Dragoon, 2nd Model Dragoon, 3rd Model Dragoon and the .31 caliber Baby Dragoon.
As I said, these Second Generation guns were all made at the Colt factory in Hartford, Ct.
The 3rd Generation Colt pistols were made by a Colt approved subcontractor known as the "Colt Blackpowder Arms Co." and are known as the "Signature Series".
Although they are officially Colt pistols and were inspected by Colt inspectors they usually bring a lower price than the C or the F series Second Generation pistols.
If I was to guess at which of the two series was most correct I would say the F series. The bluing is more like the originals.