Trailer Parking Brake Assembly. This one includes the backing plate and actuator brake shoes and the drum. The backing plate is made of aluminium as this was originally a part for aircraft servicing. Super high quality. Brake drum is 5 on 6″ pattern. PN# 51882-2 NSN# 2530-01-398-3388 Save on this one as the Government paid $847.00 for this when it was brand new 14461 L2B1