[wiswind]

I installed a new "Y" pipe on mine.
I do not remember any gasket at the Y pipe to exhaust manifold connection.
I DO remember having a problem pulling the pipe up onto the front (bank 2) exhaust manifold......and it is LOUD with a very small crack.
I would loosen all the bolts (the one by the transmission. and even the non-leaking pipe-manifold joint)...as well as the joint that is leaking.
Then....wiggle the pipe....and try to draw it up....by tightening each of the 2 nuts a turn or so at a time.....alternating between them...so that you draw up on both nuts together....maybe a LITTLE PBlaster onto the threads of the exhaust manifold studs to help the nuts to thread up nicely.

It might be a good idea to remove the nuts.....and put some anti-seize onto the threads of the exhaust manifold stud threads......only need just a bit.

If a stud has become damaged, you can buy new exhaust manifold studs at the dealer for about $5 each.

The exhaust manifold studs on the '96 have different threads on the part that goes up into the exhaust manifold....than the ones that you thread the nut onto.
PBlaster is a penetrating lubricant that I have used to soak stubborn threads when things don't want to come apart.

My '96 3.8L is at about 186K miles....and "knock on wood" is running absolutely great!

You end up with the "Y" pipe mounted solid to the engine.....no flex points.
The "Y" pipe moves with the engine......and connected to the rear of the "Y" pipe....where it has come together into 1 pipe......is a "flex pipe".
When removing the "Y" pipe, it is a good idea to use something to hold the front part of the flex pipe up....so that it does not dangle.
If the flex pipe is left to dangle.....it can damage the "flex" sections.
A new flex pipe can be bought and installed.
Walker is a good aftermarket brand.

Now......starting with the muffler (the big square/rectagle unit just behind the flex pipe) all the way to the tail pipe.....the exhaust system is all welded together as 1 unit.
You can buy the individual parts, muffler, resonator, etc.....but you have to cut the original parts apart.