Both of those engines require a wired install it is fairly easy. I have done several with Digitrax dz123's an inexpensive decoder. It will take you about 30/40 minutes to it. Unfortunately I do not have any pictures of the install and the engines are long gone out of my stable. No need to change out the mechanism unless the motors are shot. For the DL109 you really cant change out the mech for a Kato without a lot of body work to the nose. The coupler pilot (if my memory works) was part of the front truck assembly. The frame is a split piece, It has a top and bottom all you need to do is to isolate the motor electrical connections. Attach the gray orange leads to the motor, Red and Black go to the power pickups Replace the light with a LED with resistor, attach the blue and white lead to the light and your done . The decoder will sit on the back shelf of the mechanism. The Trix is straight forward install the back light shelf can be modified with a bastard file to create a pocket for the decoder to sit on. Isolate the motor and attach the decoder and your good to go. It may be possible to replace the mechanism with one of the new Arnold u28c mechanism which is far superior to the Minitrix. Thant one is a pug and play mechanism. The Kato Uc30/c30-7 mechanism can be made to work with some tweaking to get the shell to fit. How ever the Kato mech is also a hard wire install.
Bottom line: you can fit any of the newer small n/z decoders hard wired to those mechanisms
