This is a new cast iron pulley for a woods mower deck part number BC52X3/4.This is 5" in dia x3/4" shaft and the sleeve is 3/4"and it takes a 5/8" belt.I have heard of guys changing the speed of a 450 or 451 blower by changing the pulley ,not sure if this will work for that or not.This may also work on a QA 36 OR 42 to put on an 82 series tractor.