Don,
Per the 1934 American Flyer Dealer's Price List, set 950T is shown with what appears to be that engine and tender, with two 6.5 inch 4 wheel passenger cars and a 6.5 inch 4 wheel observation car. The cars shown are clearly not the 518 and 519 litho cars that came with your set.
I do not see any offerings of the 518-519 cars in the dealer's price lists after 1932. That is not to say that they were not offered in special sets, but I do not have any printed data that shows they were offered after 1932.
NWL