The mast base changed in 2004. Other than that some of the jib halyard/forestay tensioning hardware changed to allow for easier forestay adjustments while on the water.
Yes... In the early 80s we changed the step to allow for rake and again around 2004 we came out with another changed base and step casting set. The 2004 version allows even more rake, has larger stops and matched surfaces for less wear in contact points. The step cup also has small holes drilled in it that are called a "chip keeper". The chip presses into the recesses and grips the chip in place. They don't squeeze out when sailing or fall out during transport. Really cool idea by Dan Ketterman. Works great.
20640011 MAST BASE H16 BLACK
20200011 MAST STEP,H14/16 BLACK