The "L" series is the latest...The LS came before those , the LX before those , and the older ones had an L designation also but you know those because they have a different shape to the cab and i believe they were all yellow. The LX series were black and yellow, and the newer LS and L are charcoal and yellow. You can also tell by the decals on the boom arms. I am not sure but i thought the "B" designation was for a turbo,I don't know, but I would try: http://www.messicks.com/tractorservice.aspx That's the Messick's online mechanic. Maybe he can point you in the right direction even if he can't answer. BTW, why don't you post what you find out. Hope this helps - Dwain