I have it on reasonably good authority, that Dennis used Yamaha drums during the latter part of his career - probably a 'Recording Custom' set - but I can't vouch for that. However, an interview on the Mike Kowalski website provides some support for this:
http://www.bigbeatman.com/ I don't know if it's of any interest or not, but I've been told that during soundchecks, Dennis was consistent and easy to deal with. And so regardless of his drumming ablity/lifestyle, he was relatively a good pro.
I think also that Promark(?) did a limited edition of Dennis Wilson sticks.