I have now converted two of the new (first issue) cylindrical hoppers using the 6-49081 hi-rail trucks. Although one will invest about 20 bucks for a set of two trucks, I feel that, in the end, they are worth the expenditure unless one really desires the save a bit of $. The new trucks run beautifully on Gilbert track and turnouts, and the very latest version of the L-AF knuckle coupler fitted to the trucks functions very well (finally!).
Too bad they did not get it right the first time around.
YMMV.
Bob