I bought a couple tractors today and Im having trouble identifieing one of them .The first tractor I bought is a model 44 rc the serial # is 44gr31252. this one was easy to figure out. The second one I thought and was told is a model 20. The problem is the serial # is 401713 ???? I took this off the frame right where its suppose to be and this is what I get. Pointing me in the right direction would be appreciated.