ATSG Tech Manual Domestic Checkball Book Vol II: The second volume of the series of domestic checkball and small parts location manuals contain the most current valve body, checkball and small parts locations for the most current domestically used transmissions on the road today. All checkball locations are shown even when they are contained in a check valve located in one of the valve body bores. These check valve balls are often overlooked because they are not in plain sight. This manual also contains information on what material the checkballs are constructed of as well as checkball and spring dimensions wherever possible