I installed a couple of these this past weekend in my classic Lionel operating Milk Cars. Wow! Very easy project, and great instructions, as usual, from ERR.
Very cool thing is you can program it as an engine. This lets me control it from my DCS remote when using it.
I can also deliver milk anywhere on the layout now without an operating track.
Easy install: Replace slider shoe assembly on one truck with the new roller assembly from ERR.
Mount the small circuit board
Run and solder the wires to the coil
Run and solder wires to the new truck roller.
Program
Play!
Also, you can set the "energy" with which it pushes the cans out. I found on my older cars, a setting of 6 works perfectly. "9" sends the can across the layout, which could be fun in a Milk Car shootout
Here's some basic pics showing the board, and new roller on the truck.