kdog

Good day friends

I just got my first Sea Doo Speedster 1995 twin 80hp rotax and would like to know what the changes there are between engine models. Is the lower engine case the same from the 650x to the 720 and the 780 and they change the heads and jugs on the 720 and a new stroked crank for the 780 model?
I'm looking forward to the fun in the sun ride!