I've upgraded several of these cabooses with the MTH HO fan driven smoke unit. It's small and you can tune the output to put out nice smoke for an extended period. IMO, the caboose shouldn't be smoking like an engine, just a nice stream of smoke. Another bonus is the fan driven smoke unit doesn't get hot enough to melt the sides of your caboose!
I just mate the smoke output of the smoke unit to the existing stack. I use a small buck power module to power the smoke element, it requires around 5-6 volts for the heater, depending on the smoke volume you want. The tiny fan motor runs on 2-3 VDC, I just use a resistor to drop the heater voltage for proper fan speed.
