Check with Illini Replica Conversions (illinireplicaconv@ameritech.net). They have the KW Bullnose & the Peterbilt Bubblenose, and various other older truck cabs.
http://apps.aitruckmodels.com/Gallery/
Nice clead build. I like it. Want to add some quick & simple details? Add some strips of BMF around the windshield frame, to the door handles, & sleeper vents.
This is the one I purchased: http://www.pioneerplastics.com/display-cases/diecast-cases/576c/
Pioneer Plastics does make a smaller one for 1/18 scale as well: http://www.pioneerplastics.com/display-cases/diecast-cases/355c/
but this one might be a little short.
They interior domensions of the case are 15-1/2" long x 7" wide x 6" tall. Hobby Lobby has them for $19.99. The one I used was the one for the 1/18 scale cars, same interior dimensions but $14.99 and it doesn't have a "fancy" wood base.
I recently purchased on of these cases for my LoneStar, and it is about 1/4" too short inside. The stacks hit the inside of the case. These cases should be ok for my other trucks, though. My LoneStar is just a little too tall.
You can always pick uo a Marmon 57P conversion kit from AITM. Dave sells it with or without the sleeper. http://www.aitruckmodels.com/pages/ck81marmon57p.html I have one (haven't built it yet), and it's quite nice.