The el-cheapo stud finder that uses a magnet to locate nails works for finding hidden screws. The conventional way of joining the two pieces is by screws driven from bottom of lower case top into bottom of upper case. Normaly the screw heads are visible while standing on your head looking up from inside case.

Thank you, klem1. I hadn't thought to use the stud finder. At this point, after a skinned knuckle and marring a couple places on the hutch, I'm thinking I can make it work as one unit. It won't be as elegant a solution as my original plan but I think it will be fine.

One thing that kind of scared me off disassembly was that one of the screws I can see when I lie down and look up at the ceiling of the lower cabinet is half-covered by a sidewall that divides the cabinet from the drawer section in the middle. What kind of compulsive madman built this thing? I believe I have met my match, or at least have encountered his work. :)

Thanks again, and best of luck with your projects.

-- Zinnia