Some 20 odd years ago Clark Benson of Stratford Conn.made some Amfleet cars from Welz and Williams extrusions.they were 21 inches long and the Welz extrusions were too small.He made them in the coach and cafe car configurations.On the larger more close to scale extrusions he used the William ends.If anyone is interested in some spare Williams extrusions that may still be around I can put you in touch with the present owner
my email is CULLITON.BILL6@GMAIL.COM