The underside of the mower deck is contoured and free of obstructions:
Note: If a 42M Mower is installed on an X300 Series Tractor that was equipped with a 38X Mower, one M155044 RH/LH lift arm is required; the 38X Mower uses a unique right-side draft arm. Also order AM136646 lift-assist spring kit if the tractor is not already equipped with it. This would normally apply to a tractor previously equipped with a 38X or 42X Mower deck, X300 less-deck model, or model year 2006 to model year 2009 (serial number 010001-150,000) X300/42M Tractor.
Replaces BM21893