Essentially, the Command Trac system is a part time 4wd transfer case with a high and low range. On YJWranglers, XJ Cherokees & Wagoneers and MJ Commanches the Command Trac transfer cases used are the New Process 207 (earlier models) and the New Process/New Venture 231. These transfer cases are aluminum bodied and chain drive. The fluid used is ATF.
The Command Trac system is a part time one and really should not be used in the 4wd modes when driving on pavement.