Ken, Perry:
My repair guy, Jan Willard, has finished with the S-2a mods. This turned into a very expensive project, for a couple of reasons. The worst of the problems was that apparently the rods are tied to the drivers with rivets that were soldered to the rods after the heads were pressed over. He also had to rebuild the front truck to get the model to track well. If your models don’t have those issues, life gets better.
The backhead is something I just will not do without, but it’s sometimes an expensive proposition, because in models like this one, the boiler must be extended back into the cab to locate the backhead in the correct position. Note that trying to solder a boiler extension inside the cab is a hopeless task, so Jan uses JB -Weld for that and for mounting the motor. JB Weld will withstand any baking process for Scalecoat (400F “glassification” temperature), but can be lifted by some really aggressive cleaning regimens, so you MUST discuss such mods with your painter!