What is the difference between a Wurlitzer 140 or 140b and a Wurlitzer 145?

The only true difference between 140-series and 145-series Wurlitzers is the amplifier. Both keyboards were released in the 1960s and represented a total redesign of the Wurlitzer electronic piano. Wurlitzer overhauled the mechanical action, revised the cabinet, and — for the first and only time — manufactured two parallel styles of amplifier: a solid state amp (the 140/140a/140b) and a tube amp (the 145).