I too have an 86 Mariner 3297. I love it. Plenty of little projects, but what boat doesn't have these. Structurally sound, engines are great (same Crusaders as cmariner32 above) Enough room to sleep 6, but gets kind of crowded. I don't have the gas tank issue mentioned above. Handles great, twin engines are the only way to go... but these are perfectly powered for this boat, not speed demons, but can comfortable cruise at 3200 rpm and go about 23 mph.
Working on the engines or in the engine compartment is a breeze with the way they are located under the rear deck area. I had a little blistering on the gel coat, but a good sanding and 3 coats of bottom paint has cured that and last 2 years haven't seen any signs of blistering when hauling out for the winter.