The kit comes with two draft gear boxes for the couplers. One is shown in the next photo with the lid snapped into place.
The coupler box fits perfectly in the underframe. If you go that route, it is an easy installation. The photo just shows the part in place, but I didn't use it.
My current fleet standard is the HO-scale Proto Max coupler by Walthers. The coupler box is just a hair wider than the opening provided in the underframe, so a quick filing of the sides of the underframe took care of that. I also had to cut off the two screw mounting holes on the side of the coupler box to clear it with the air line. I don't use those holes anyway, so it was no big deal. I used the Xuron rail nippers to cut those off. A little filing of the coupler box and it was ready.
I then tapped and drilled a hole for the coupler mounting screw and installed the coupler. What I did notice was that on an extremely tight curve, the coupler may hit the air brake valve. If this becomes an issue in the future, I may replace the valve with a rubber one.
The underframe already has a starter hole for the truck mounting screw, so it was just a simple matter of drilling the hole deeper and then tapping it for the 2-56 screw used to hold the truck in place. The photo shows the two screws. My trucks aren't ready to be installed yet, so I will leave them off while I'm building the car. I decided to not let the screw protrude through the bottom of the car, so I will probably have trim the screws' length later on.
The next step is to place the wooden board section on the top of the underframe. I needed to remove some flash, but they fit rather well. I put a weight on one end and used superglue to fasten it. After a few minutes I moved the weight to the other side of the part and completed supergluing the part. When the parts had had enough time to dry, I carefully filed the edges flush with the underframe.
Installing the steps was no problem. I only had one of them that needed a bit of filing to fit snugly into the slot made for them in the underframe. While holding them in place, I applied a drop of superglue. The instructions state to brace the steps, but I think they are in there pretty well. The kit provides you with one extra step part should you loose one in the future.
The brass end walls need to be bent to shape. The brake wheel stand needs to be bent in a bit to be parallel to the end wall of the cabin. Next, I superglued to the brake wheel housing to the brass wall. The bottom of the housing needs to be even with the bottom of the lower horizontal part of the brass brake wheel stand. I did that for both brass walls.
The brass brake wheel's center hole is too small for the brake wheel housing, so it needs to be drilled out. It doesn't take but a couple of spins of a hand drill to open it up. I used a piece of scrap wood onto which I did the drilling to prevent the wheel from being bent out of shape.
Next, I glued the brass wall to the end of the underframe. This was quite tricky, trying to hold the car, trying to hold the brass part, and trying to apply just the right amount of superglue. The method that worked for me was to put one tiny drop of superglue in one spot and hold it in place. Then the part sticks to the car and the rest of the wall part can be glued. I also put a dab of glue where the brake wheel stand hits the floor of the car. That provides some intermediate sturdiness to the construction. After I did both brass wall parts, I cleaned up and installed the plastic "cover". Again, that, too, was a bit of challenge to get on there, and hold it straight while applying the glue.
There is a rectangular cover that surrounds the coupler that needs to be installed next. It was a bit hard to photograph, so the image was overexposed, but I highlighted it in the photo. Since I didn't feel like removing the coupler, I just cut the bottom part of the rectangle off and install it. It looks to me like the Kaslo photos of the model that come with the kit showed the same thing.
There are a large number of horizontal bars that need to be installed on the brass end walls. The kit comes with thin brass strips for these, but it looks much better using real brass wire. I just formed the brass wire to look like staples and then inserted them, installing them with superglue. This photo shows the first two in one wall. After the glue cures, I used a pair of cutters to trim the wire on the back side.
The grab bars on the left side have to be bent in several 90-degree angles. The right side of the bar is flush with the brass wall. The left side, however, sticks out. This is so that the bar lines up with the roof overhang. The left side also bends up and then over to insert into the existing holes in the brass wall. I must admit that I didn't get these right until my third try! I had installed them all and I was working with the model well below my eye height. Then when they were all done, I held the model up to look at them head-on, when I discovered that they were all crooked. The two 90-degree bends need to be very small and very close together. Hopefully the photo will help.
I couldn't figure out why I had some square and U-channel shaped parts left over from the kit. It wasn't until I started to study both model and prototype photos that I discovered that they are to be positioned behind the brass wall. The photo isn't very good, but you get the idea. Because the grab bars were glued through the holes in the brass end wall, I had to use a grinder on the Dremel tool to grind down all the material that poked through so that the styrene pieces could be glued flush to the back of the brass wall. Some of the U-channel parts were warped and required some special care to get them to be as straight as possible.
In the prototype photos I noticed there was an extra grab bar near the bottom of the car's ends. These are not provided for in the kit. I drilled some holes, eyeing it mostly, and tried to bend some wires. I got one in there to fit after about three tries. When I did the second one, I had made about 5 or 6 before I gave up. Those were hard to bend and shape. I finally decided that I could just mimic this tiny detail by simply gluing some sections of brass wire directly to the ends. Probably not good enough for a contest model, but certainly good enough from a foot or so away.
I had previously posted on this web site that I had bought a pair of brass trucks that were made for this car. I tried for several days to deal with the fact that the brass trucks had shrunk during the manufacturing process, which meant that the critical distance between the truck's sideframes was too short to fit a standard set of wheels in it. I finally just gave up. I also noticed one day that the caboose trucks that American Models carries are a lot closer match to the prototype cabin cars photos I had seen. I ordered a pair of those. They also provide the ability to pick up track power through the wheels. By positioning the wheels such that one truck picks up power from one rail and the other from the other rail, it is possible to provide electricity to the lights in the cabin car. When I placed the car on the track, I noticed the couplers were way too low, as is evident in the next photo showing the car on my coupler gauge jig. The top of the coupler is supposed be even with the top of the block of wood. I resolved that by adding some washers and a nut to the screw that attaches the truck to the body. There are two small pins under the American Models truck that I had to cut off to get the washers and the screw to fit.