We just bought a Massey Harris 50. We are trying to figure out what year the tractor is.  Looking at the serial number, the second number is an "I" rather than a number one. the entrie serial numer is SGM 5I3693.   There is no yellow paint indicating that it is an industrial model. We haven't seen any where that they even made an industral model, so we can't figure out why they would have put an I rather than a 1.

Hi Jeff,        My Massey Harris 50 is serial number SGM 512190 and both the ones look like  letter "I's.  I think this is just a quirk of the number stamping set that was used.
Based on my Serial Number data books it would appear  both our tractors were made in 1957.           Best wishes, Alan Painter, Brownsville, Oregon