Wow.

http://book-graphics.blogspot.com/2013/04/frankenstein-illustrator-berni-wrightson.html

Here's a site where someone nicely presented virtually all the FRANKENSTEIN and the LOST FRANKENSTEIN PAGES in a size where you can really appreciate them.

For those who want to purchase the book and haven't, the 1983 Marvel softcover is complete and correct. The 1983 hardcover is not.
In the 1983 hardcover from Dodd-Mead, there are two double-page spreads at the very beginning and end, the first with Frankenstein alone in a forest, the second with Frankenstein at the North Pole standing on the ice watching the ship sail away on the horizon.
I bought the hardcover when it was released, and only later learned that the softecover was more complete. The hardcover only has one page of each of the two double-page endpapers. The Marvel paperback version has the double-page spreads complete and correct.

Probably that was fixed in the later Dark Horse hardcover, but I haven't seen it, or at least not that I remember.