One new aftermarket replacement horizontal exhaust pipe fits Ford New Holland tractor models: 4000 (1961-1964 with 172cu.in. gas engine, except inline), 800 SERIES (1958-1962 with 172cu.in. gas engine). Industrial / Construction Model: 1801 (1958-1960 with 172 CID GAS engine) Technical Info: Dimension A (1) A: 1 3/4″ INLET ID Dimension B (2) B: 24″ VERTICAL LENGTH Dimension C (3) C: 29″ HORIZONTAL LENGTH Dimension D (4) D: 1 3/4″ OUTLET OD Replaces Part Number: 311051 Models This Part Fits: 1801, 4000, 800 Reference Numbers: 311051, 311051-A