PACCAR Incorporated (PACCAR) is recalling certain model year 2014 Kenworth T660, T680, T700,T800, T880, W900, T440, T470, T370, T270, T170, C500, and C550 chassis manufactured between August 7, 2013, and October 31, 2013, and Peterbilt 320, 325, 330, 337, 348, 365, 367, 382, 384, 386, 388, 389, and 587 chassis manufactured between August 7, 2013, and November 3, 2013, and equipped with IMMI-brand L9 seat belt buckles. When the button is pressed to release the seat belt, the latch plate can become partially engaged with the buckle, making the seat belt difficult to unlatch. Thus, these vehicles fail to conform to the requirements of Federal Motor Vehicle Safety Standard (FMVSS) No. 209, “Seat Belt Assemblies.”