Keep in mind that newer reproduction serial tag plates are flat - originals were acid etched, so ended up with raised lettering. I looked and called all over the place trying to get one replicated with raised lettering...but sounds like it is not possible due to laws govering the usage of the chemicals used in the original process.
Here are two pics. The reproductions are available at www FordsonHouse DOT com. We bought one from a junkyard as we wanted to keep the look of an old, worn one - having the correct serial number did not matter to us as much as having that old look (we are keeping our Regular rusty - it will never be repainted). My husband will have to do a little repair to the holes in the plate though.
And yes, the serial number for your tractor should also be stamped into the top side of the left frame near the area of the radiator.