I was also a big fan of the die cast hoppers that Kline and Lionel have issued in the past. The problem I discovered is a simple one.......they are too darn heavy. Yes they are very nice and detailed and feel great in your hands but once you put ten or more on a train and if you have say a 2 1/2% grade on your layout they will lift the front of even your biggest steam engines up so if you go over a switch or go into a turn your steam engine will derail.
I now stick with the new Lionel plastic body 2 bay hoppers (GLa) and the derailing problem never happened again.
However if you still like the die cast hopper you probably can pick them up for a good price at train shows or auction sites as I think a lot of modelers have discovered the weight issue with die cast.