One New Replacement Chrome Double Wall Muffler (Straight) that fits John Deere Tractor Models: M, MT, MC, 40, 320 (STRAIGHT PIPE, NOT MUFFLER) 2-BOLT FLANGE MOUNT. The pipe is 220″ tall – with an outside diameter of 3″. The inside diameter of the pipe is 1-7/8″. This pipe is double walled to help protect the outer chrome pipe from discoloration from the heat of the exhaust. Replaces Part Number: R4259 Models This part fits: 320 Reference Numbers: Chrome Mufflers, Exhaust System, Mufflers, R4259