There was a time around the late '70s early '80s when something like particleboard was used for the cabinetry. When it gets wet, it swells up and fails. There are some threads about that here on WTW I believe. That may have something to do with the gap between the early and more modern used Alaskans out there for sale. It wasn't actually a design fault as much as it was a maintenance issue. The roof vents can leak if the sealant isn't replaced over time. Same for front/rear drain channels, etc.
Alaskans are often compared to an old wooden boat interior....and just like that old wooden boat, you have to maintain the watertight integrity of your Alaskan.
Cab/Overs were not produced from Day One so finding one of them is even harder and they tend to have additional wood damage (rot) on them. My suggestion for an interested buyer is decide if they want a CO or a non-CO, then the first criteria is to make a detailed survey of the interior and if you find rot/mold, etc. pass on that unless you are desperate for a complete tear-down project. As important is the condition of the floor; if the wood is "soft" and if it is still solid where it meets the sides, front and rear of the lower section.
I searched for a year or so before finding one only 30 miles from me only to find it was sold to a guy who was one email ahead of me. A few months later, after I mentioned that I missed it, the buyer decided to go in a different direction an he contacted me. I went to take a look with my truck and a wad of cash and bought it immediately!
Go on CL and search from Washington to San Diego using every town you can and search just about every day....you will get a good idea of the cost and the condition of all Alaskans probably before one pops up but be prepared to jump on it as they don't hang around very long if they are nice ones....the trashed ones are there for EVER but stay away from that kind of project!