Examples of sliding hitch assemblies, and locking mechanisms therefor are disclosed. Sliding hitch assemblies include a pair of slide rails slidably supporting a fifth wheel. Each of the slide rails in turn includes a driving position locking pin that selectively locks the fifth wheel in a driving position, and a maneuvering position locking pin that selectively locks the fifth wheel in a maneuvering position. A cam member is slidably mounted inside each slide rail, and includes a first cam surface that unlocks the driving position locking pin when the cam member is in a first position, and a second cam surface that unlocks the maneuvering position locking pin when the cam member is in a second position. The fifth wheel is mounted on a pair of downwardly facing U-shaped members slidably supported on the slide rails, and a wear block is interposed each slide rail and a corresponding one of the U-shaped members. An adjustable element may be moved relative to the corresponding one of the U-shaped members to stay adjacent the one of slide rails as the wear block wears during use.