I checked again, and according to Wilson the Police Positive Special and the Detective Specials shared serial numbers with the first gun made in 1965 being 861,500 and the last one being 890,799. Both of the guns mentioned in this thread fall within that range.
The 1966 models started with 890,800 and during this year the gun was redesigned and the letter D was added as a prefix. Th new model started with number D900101 meaning 200 old models were made in 1966 before the revamped design started production.