Intro
I have captured how I converted the tender coupler on this locomotive. The locomotive's front coupler is a dummy one and that is fine with me.

Removing Old Coupler
The conversion is fairly straight-forward, but it is not trivial. This first photo shows the truck with the old Rapido-style coupler removed from the tender underframe. This is done by popping out the middle wheel and removing the screw that holds the truck to the underframe.

The next step is to remove the old coupler from the truck. I tried popping out the coupler from the coupler body but was not successful. I used a thin razor saw and cut it approximately where the line is drawn in the photo above. A little filing is all that is left to do to complete the work on the truck.

Installing New Coupler
Here are the parts for the conversion. The truck was re-installed on the tender so that I could determine if a shim was needed. I used the Micro-Trains 1015 coupler. You can also see the Micro-Trains coupler height checker tool.

Well, as you can see from this photo, there was a substantial height difference between the under side of the tender frame and the ideal vertical location of the body-mounted coupler. As a matter of fact, the height difference turned out to be 0.050".

Here you can see the coupler being installed. The hardest part was getting the coupler to lie still on the tender body so that I could apply the glue. The white under the coupler is the shim. This will be painted black in the future. I used Testors Plastic Cement to mount the shim to the body. I tried all sorts of ways to hold the coupler still and in position, but nothing worked. Then I thought about balancing something across the coupler. A toothpick turned out to be the perfect weight match. Then I lightly touched each side of the coupler with a small brush wet with the Testors glue and let it get a better grip. After about 20 seconds I came back with the brush and put on more glue. I took this photo while everything was drying, and I don't dare touch it until tomorrow! :-)

Update: While I was installing weights in the tender, the coupler fell off. Glue doesn't seem to work too well. I took the time to install the coupler using the Micro-Trains screws by drilling a hole and tapping it. It works great now. It looks like the coupler is still too high.