Hi, I've been lurking around this board for a while now and have read the majority of what has been posted.  Thanks for all the great information!  We bought a 2001 16' a couple of months ago and are now trying to replace the rivets and screws.  I have read all the posts about rivets and I think I'm ready for that part.  We tried some of the screws already but I haven't seen any posts about those.  Some go into the upper cabinetry in the rear and we have replaced some of those.  Some go into structural support for shelves, etc. at the front, but some just disappear and I can't find the inside point at all, both in the front and rear.  Any ideas about what these do and if I should just try to pull and replace without finding the ends?  They are all rusty and no longer have caps or collars.