The next step is to attach the body to the walkways. This was actually my most "scary" moment in the project, because you don't want the body to sit crooked on the walkway. I did a dry-run first, including clamping, etc. The photo below shows the set-up as the 5-minute epoxy is drying. I used two sets of pieces of wood to hold the whole assembly off of the work surface so that I could get the clamps on. I found a piece of scrap wood that fit under the walkway, inside of it. Do not put pressure on the outside lip of the walkways. This is important because, without this, the clamping caused the walkway to not connect to the body correctly. By placing this piece of wood under it, it forced the walkway to match up with the body.
I then used 3-inch C-clamps and some spare wood and metal weights to provide the counter force for the clamping. I made sure that the body sat in the center of the walkway, both in the front and rear and side-to-side directions. Don't use too much force or else you'll distort the parts. After the parts were attached, I came back and filled in the larger gaps with 5-minute epoxy. Later, when the body is painted, the gaps shouldn't be visible.
The engineer's side (right-hand side) of the body has a rectangular hole in it that is supposed to receive the air filter part shown in the next photo.
The hole and the part required some filing on my model to be able to get the part to fit. I used 5-minute epoxy to glue the part in place. This close-up photo shows that the part doesn't really fit perfectly. You may need to work on yours to make it fit better. On my Pennsylvania Railroad prototype the majority of the RS-1 engines used a cab signal equipment box mounted on the walkway. I installed the air filter part for completeness of this documentation, but for my particular situation, I could have left it off altogether.
I fabricated the cab signal equipment box out of 0.020" styrene sheet and some styrene square tubing. This first photo shows the inside construction. It took some careful measuring of the actual body shape to craft this box to fit just right. The front face of the box is supposed to be flush with the cab's side wall.
This is an upside-down front photo of the box. I used some 0.005" thick see-through plastic to simulate the two panels of the cab box that can be opened, presumably to gain access to the equipment inside. I used some thin bronze wire to simulate the hinges. If I had known ahead of time that I needed to build this, I might have ordered some hinge detail parts (I believe Precision Scale Co. makes them, but don't quote me on that).