There is currently no single kit for the "Smoky & the Bandit" Kenworth W900. That being said, it can be made with the frame, engine, hood & sleeper from the AMT Kenworth W925 kit, the cab from either the Revell of Germany W900 or T900 kits, a tandem torsion bar suspension (if your AMT kit doesn't have one) from either P&P Resin Works or Melbourne Model Truck Accessories, and the gold decals from Model Truckin'.
Here are the links:
http://ppvintagekits.com/
http://www.freewebs.com/mmtaer/
http://modeltruckin.com/store/
There is some debate as to the engine type in the actual truck (since they used three trucks fro the movie you have some options). You can go with the NTC350 from the AMT kit or a Caterpiller 1693TA from KFS.
Have fun!