Preparation
This is definitely one of the easiest coupler conversions out there. The Bowser models come with body-mounted N-scale Micro-Trains-style couplers. I am going to replace them with Micro-Trains' MT-905 Z-scale couplers (my fleet standard). The first photo shows the tools and parts needed. I use a small screwdriver to remove the old coupler screw and install the new one. The small rail nippers are optional. I don't use magnetic uncoupling, so I remove the metal hook from couplers. The rail nippers are for that purpose. The file is also optional. Sometimes, after cutting off the metal hook, I like to file the hook for a cleaner look. If you use magnetic uncoupling, then you must leave the hook as-is. The hook cannot be completely removed from the coupler otherwise the whole coupler falls apart.


This is the bottom view of the caboose. As you can see, it is straight-forward. I removed the caboose's roof (falls right off) to help stabilize the unit (not shown in the photo).


Removing Old Coupler
As you remove the screw, the coupler may fall apart as shown in this photo. I hang on to these old couplers, because you never know when you need the special plastic shapes in the future...


Installation and Completion
This photo (extremely low-light condition) shows the N-scale coupler on a caboose and the Z-scale coupler on another. The screw that comes with the Bowser model is too long and is visible above the caboose' decks. The Z-scale coupler comes with a shorter screw, which doesn't break the decks' surface plane. Because the hole in the caboose is designed for an N-scale coupler, the Z-scale coupler's draft box is set back from the rear/front edge a bit. This makes for very close coupling. Personally, I like this because it is more prototypical.