Based ont the fact that the serials of the last No.2's produced during the civil war were around 40,000 and that, according to Gary, the production rate after the war was of roughly 5,000 per year, the guns in the 55,000's range should have been manufactured in 1867-68.
This confirms what Gary also wrote about an example within 200 of my serial number being shipped in 1867.
Besides that, having read in some Colt letters that at this time, guns could stay in the factory stocks for several years before being shipped, what opoefc writes about No. 55578 being shipped in 1870 is also very credible.
I don't think that the 3,167 guns ordered by France in 1870 were immediately manufactured in emergency to be delivered the same year. They very probably came from old stocks.