The gon under consideration is the old Mantua car. It was also part of the
Mantua Tyco line but it did not make it into the Tyco Tyco trainset
line...AFAIK they used a copy of the typical
Bachman/LifeLike/Rivarossi/Roco/Mehano 40' lower sided car.
Model Power might have the tooling but it may not be usable as it hasn't
been run for decades.... Since Model Power has several cars in their line
already I wouldn't look for them to bring out the car... but you never know.
Charlie Vlk