I am going to put a new tail light peice on my 66 bug. The old one is rather rusted. I have the new bit, but the old one seems to have some sort of ...something, beading, tubing, joining, seperating type thing between the metal of the tail light and the metal of the body. This is also between all of the other parts of the body, and since I plan to take the thing apart one peice at a time, fix rust, and put it back, I need to know what it is, and how to get it.

they are taillight seals give george at classicveedub a ring only about $14 a pair or look at his website at http://www.classicveedub.com.au 

Are they generally reusable, or do I have to replace them when I take the tail light peice off?

if they look like crap, replace them .. but for 14 bucks.. you cant go wrong..

knee bone's connected to the thigh bone, thigh bone's connected to the hip bone, hip bone's connected to the back bone......heheheh.
sorry. that was completely unneccesary i know. but i couldnt help myself./