Purpose??The purpose of this test procedure is to provide a means for evaluating the drivetrain of the passenger car being wrecker-towed under a variety of road conditions. Wrecker towing attachment is evaluated by conducting SAE J1143@ Towed Vehicle/Wrecker Attachment Test Procedure??Passenger Cars. NOTE: For the purpose of this test procedure@ the drivetrain refers to the combination of a specific transmission (make@ model@ size@ type)@ a specific differential assembly (make@ model@ size@ type)@ and if required@ a specific propeller shaft (make@ model@ size@ type).