The upper photo is the older version and requires the frame to be modified to get any decoder into to it.
The mechanism in the lower photo is the later version which accepts a board type decoder.
Sometimes it happens that someone gets the wrong decoder because they are mistaken about which version they have. While the board decoder can't be used on the older version there is no reason a wired decoder can't be installed in the newer version.
A small section of the circuit traces are removed in the seven locations shown in red in this photo to isolate the various functions.
Then the capacitor that is installed across the short hood end is removed. This was added by Kato after it was realized that when running at high speed on DC the trailing end bright white LEDs would flicker. Since this is not going to be an issue using the decoder it can be eliminated.
Next an additional resistor needs to be added at the location shown in this photo. The value on the resistor should be the same as the existing one. They will have either a number 271 (270 ohms) or 561 (560 ohms) on them. I got mine from other stock Kato boards I had but this type of surface mount resistor can be purchased from Electronics supply sources.
All of the decoder wire connection locations are also shown in this photo.
This photo shows how I placed the decoder with the wires facing backward but it could go either way. The wires can either go between the leads of the LED or around to one side.