One New Replacement Muffler for Case Crawler Dozer Models: 450C, 455C, 550, 550E, 550G (Serial Number Below JJG0255794) Non-Turbo Machine. The muffler inlet has a backing plate with 4 holes. Tech Info: Inlet Length: 4.00″ Inlet ID: 2 1/4″ on 4-Hole Base Plate Body Length: 8.00″ Outlet Length: 5.00″ Outlet OD: 2.00″ Overall Length: 17.50″ Replaces Part Numbers: A172785, A170073 Models This part fits: 450C, 455C, 550, 550E Reference Numbers: 1717-1205, 1717-1205-A, A-A172785, A-A172785-A, A170073, A172785, A172785-A