My K100 was designed with some specific finishing details in mind that are left to the modeler to add. If you have one of my K100's already, or plan to buy one, I will explain how I intended to finish this model.
First, the handrails could have been designed into the truck cab, but I felt it would look much nicer with a free standing detail made from wire. I use .010 wire on my trucks for mirror brackets and other details like railings. On the K100, there are 3 sets of brackets to hold the railing to the side of the cab, which I designed into my N scale version. I also designed a #80 hole right above the top set of brackets. Using a prototype photo, I bend a wire into a railing, that can be inserted into the #80 holes, and then glued to each bracket to hold it in place. It's a bit tricky, but it can be done. I use a #80 drill bit to clean out the holes after painting.
It seems like most cabovers in the 1980's had stripes or multiple color paint schemes. If someone wanted to spend the time to create a set of stripe decals for these trucks, that would be great. However, I plan to paint mine a solid color, or maybe two tone.
Cabover trucks generally have a large opening in the rear of the cab where the motor is located. I did the best I could on my model as I don't have any motor detail, and didn't want to leave a hole in the back of the cab and not have anything inside to fill it. I did leave two openings for exhaust and air cleaner details. The K100 has an air filter that is located on the driver side, which you can see on my model. The air filter is usually fed by a stack on the back of the cab to pull in cold air from above roof. The stack should be located on the rear of the cab, on the driver's side. If you plan to do a single stack exhaust, locate it on the passenger side of the cab. I plan to do dual exhaust on mine, which will be made from brass or aluminum rod. Each stack should have a 90 degree bend on the bottom which can then be glued to the inside of the cab. Refer to the photo below to see how a typical dual exhaust and air intake are configured on these trucks.
If you want your own N scale Kenworth K100, check out my Shapeways Store: K100