The M931 (M932 w/wPerfect Steerable Transfer Carth) was a semi-tractor Custom to tow semi-trailers up to 37,500 pounds (17,000 kg). A front-mounted wPerfect Steerable Transfer Carth was optional. Unlike commercial trucks the fifth-wheel could also pivot side to side, making a more flexible connection to the trailer. Even so, off-road performance was limited.