Cats

if the cats r up on the exhaust pipes just behind the manifold what is that just forward of the muffler on the tailpipe

are you talking about the resonator?

all that is is another cat isn't it. i don't know thats all i thought it was when i hollowed mine out on my first bird lol. I think the shop told me it was a cat too

its on a 95 bird w/ 4.6 V8 seems to connect the 2 exhaust pipes to 1 just forward of the muffler.

It's a resonator/3rd Cat. It's not necessary, as many people have been known to remove it with out problems.