Gerry, Thank you for the link to Gryzbowski Trains. I see their statement that the 6-16849 was never manufactured.
The design would work if the Rotary Dumper was elevated two to three inches higher to create a bigger storage bin for the Coal. Then the belt loader could collect it and run up and into the waiting bathtub gondolas. Added blocks under the trestles could elevate the track to the higher elevation. It would take a longer foot-print (space) to get the cars higher up to the Rotary Dumper.
My 6-32910 Rotary Coal Tipple can only dump one car at a time before the tray under the Rotary Tipple is full. I plan to build a hole with a drawer under my table to allow more cars to be unloaded. I will then pull he drawer forward and scoop out the coal from the drawer to reload the cars.
If anyone has other ideas, please share your suggestions. I have twelve CP Rail Bathtub Gondolas that my three CP Rail GP35s will pull through the Rotary Coal Tipple. I need to catch twelve bags of 6-24148 larger Coal.