The Tender
You can keep the original tender chassis, with its pick-ups, and put a new body on it. Or you can replace the whole tender, my tender with trucks will work.
I have designed a new body that can be used with the model's original chassis. To use this, you have to cut away the original body from the chassis. You also need to unsolder the wires the wires from the chassis, ans use some extra wire to extend them before re-soldering them (about 2cm will do).
The new body is designed to sit on the weight in the tender, it will need some glue to keep it in place.
There is a mount for a Micro-trains 1015 coupler at the rear.
At the front, drill a hole in the front and insert a piece of brass rod (or similar) bent over to form a coupling to engage in the locos drawbar.