Ron-I have yet to try it out myself, the cab that drew is talking about is a resin cast one from http://www.10-8hobbies.com there are a couple of sites that you can get them from. Firemodelman would be the one to ask about that, he seems to be pretty good with doing the bodies and such.I'm still learning and planning before I jump into it.
Drew, i don't know if you have seen this site before http://www.mtfaco.com/ but I know someone said you can get chasis from them along with alot of other stuff to. One other site I have is http://www.emergencymodelcastings.com/Index.html. Hope those help you a little.