[Your local Freightliner or Kenworth dealer.]
[An independent truck equipment dealership.]
[Online retailers such as TruckPaper.com or CommercialTruckTrader.com.]
To find a relevant business, you can either search for "truck cab for sale" or "truck sleeper for sale" online, or you can inquire with a Freightliner or Kenworth dealership.
Keep in mind that the cost and availability of new cabs or sleepers can vary depending on the make and model of your truck, the dealer, and any desired customization or modification options.
