The part number for the tender wheel is 700E-10, the part number for the tender axle is 700T-20, and the part number for the tender wheel and axle assembly is is 700E-33. The tapered axle, 700T-20, shows up in the Lionel Engineering Standard, dated 1966, as a tapered axle. There is no straight axle shown in the Standard. Based on this I would say that the straight axle was designed and used after the postwar era ended,
The OD of the wheel tread is 0.750” and the OD of the flange so 0.900”.