Hi,
There have been a couple of changes to the engine. The prop hub is one change. It no longer has the long skinny steel hub, it now has an aluminum hub that will hopefully be less likely to bend. The newer engines come with a different carb block that rotates the engine so that you don't have to use a bellcrank on the throttle linkage. The carb is also different, the new one has a choke. Not sure if the size of the carb is different because I no longer have an old style to compare it to.

Other than these, I am not aware of any other changes. As far as value, you can get the newer models here on RCU for $200-250. I would say $150 would be a fair price for it. Of course that is just my opinion.

Hope this helps,
Alan