I have a MH33D and the serial number itself does not really lend itself to all the info i have seen online.  My serial number is 12429P, as its a 5 didget number it deosnt really fit into all the other information i have seen.  Can anyone help me sort out what year this might be?  Thanks! 

Hi Johnnymac1,

According to Keiths data book it looks like your tractor is a 1955 very close to the end of production.  I believe the "P" is for the type of diesel pump used on your tractor.
Joe

Joe is correct.  The "P" means it was equipped with the Bosch PSB fuel injection pump.

Mine is an earlier one.  Serial Number

D1RF 9306P

JB