I have a few Pietta 1851 Navy .36 revolvers with varying date codes; AZ/1990, BH/1996 (pre-CNC machining), CM/2014, CN/2016, CP/2017, CS/2018, and CT/2017 (CNC machined). I have an affliction known as "parts-changer syndrome" as I like to move parts around and have created a few Confederate "type" revolvers that Pietta never marketed: Leech & Rigdon, Schneider & Glassick, Rigdon & Ansley, and Augusta Machine Works (last two with 12-stop-slot cylinders).
I don't where Old South got the 2000 date from as Pietta (and Uberti) went to CNC machining ~2002. Prior to that date, Pietta would sometimes sub-contract parts from the various small Northern Italian manufacturers for its production and would have to fit said parts to the revolvers coming off their line. Old South's reasoning for that is, presumably, for litigation purposes, IMO. CYA, if you will...
I created the two 12-stop-slot cylinders using Pietta plain (non-engraved) cylinders with no rear safety pins that are pre-CNC. Both fit any of the CNC revolvers I have. The cylinders are the same length, diameter, arbor hole diameter, et al. The differences will be in the timing of the bolt, the stop slot width, and the hand length of your revolver. The problem is fairly easily rectified with judicious use of needle files on the bolt head (primarily).
It is not, to borrow an old phrase, "plug 'n play", but it
is close.
I primarily use VTI:
Pietta 1851 Navy - VTIGunparts.com Online Store as my parts source: fair prices and fairly well stocked even in these lean times. Give them a call.
This is my Pietta R&A .36 that I "created" using a Pietta 1851 Navy .36 steel frame CP/2017 revolver, with a part round/part octagon barrel from VTI (from the Pietta Griswold & Gunnison .36 revolver), and the pre-CNC cylinder described above:
Sincerely, good luck with your endeavor!
Regards,
Jim