TM 9-2320-302-20 0021 00-21 Table 1. Unit Preventive Maintenance Checks and Services (PMCS) for the M915A3 Tractor Truck - Continued. ITEM NO. INTERVAL LOCATION PROCEDURE NOT FULLY MISSION CAPABLE IF: ITEM TO CHECK/ SERVICE 41 (Con’t) Annual Rear Axles, Differentials NOTE There may be approximately 1 pt (0.47 l) of lubricant remaining in filter ele- ment. Be careful not to spill it when removing element. b.  Use    a    suitable    filter    strap    wrench    to replace  filter  element  (32)  from  forward- rear axle differential. c.   Install plugs (31) and fill differentials with gear  lubricating  oil  (Item  22  through  25, WP 0235 00) until level is even with filler plug   (28)   openings.   Use   the   following capacities as a guide. Do not overfill: Forward-rear 13 qt (12.3 l) Rear-rear 14.5 qt (13.7 l) 42 Annual Front and Rear Wheels, Wheel Bearings Remove,   clean,   inspect,   pack,   install,   and adjust wheel bearings. 43 Annual Front and Rear Wheels, Brakeshoe Linings Check    brakeshoe    linings    for    a    minimum thickness  of  1/4  in  (6.5  mm).  Replace  worn or damaged brakeshoes. 44 Annual Front Axle, Stop Cushions Check  front  axle  stop  cushions  for  wear  or deterioration. 45 Annual Data Plates Check data plates to ensure legibility. 46 Annual Collision Warning System (CWS) Align CWS antenna (WP 0110 00). 28 31 32