Are the hulls for the 28's the same since it first came out in the beginning. Are the early 80's the same as the late 90's as far as strakes, chines and the hull bottom?

Yes, they are from the same, one and only, mold!

The lamination layup scheme and the materials used has changed through the years though.

Newer ones are alot lighter than the older models due to the above. Plus Pepe finally figured out how to do fiberglass after 20 years!! Ha ha ha...just kidding Pepe!