[A/S] 65 Overlander Underbelly Suprises

[jclos@xxxxxxxx]

We had some hard rain here in Arizona lately, so I started checking 
out the rear of the Airstream looking for any leaks.  I found what I 
was looking for (lucky me!).  It seems that the rain ran in the back 
by getting in on the top of the bumper (sewer stuff) cover.  I noticed 
an old gasket there, but it is old and brittle.  It seems that this 
has been happening for a while on this trailer that was "just like it 
came from the showroom" as I was assured by the seller.  Lots of rust 
and metal rot under the bellyskin.  I started drilling out rivets and 
started dropping most of the skin under the rear.  I found a tin 'tank 
cover' ,under the bellyskin, and it surrounds the black tank.  I don't 
know what the purpose of this is, but I may find out more tomorrow (as 
the project unfolds).  I do have a few questions for the group, as I 
have noticed posts from folks that have done this before:
I want to cut the skin and then screw (not rivet) back some new 
patches after I have lost all my patience and emptied my wallet.  What 
have you used to cut the skin?  I hope I can get the screws started 
and tight when I replace the skin. 
I see some rust on the frame members.  How should I try to treat that? 
What is the best place to try to find some Velkum?  I think I have a 
slight leak around the black tank vent out the top.
I also want to replace the cracked drain pipes from the tank valve 
out, and from the tub out.  I glued the cracks, but since I'm in there 
I may as well replace that stuff.  Is that funky 'Y' a standard drain 
type and size?
Any suggestions and advice will be greatly appreciated!
Thanks,
Joe Clos