My left tailpipe is loose...

I had the same problem, and it was the old gasket...making too much space. There are typically two types of gaskets....flat and "donut" (for lack of a better term).
Mine used the donut, found at common auto parts stores. Take your old one in to compare. The thickness of the new donut solved the problem.
Chuck

The problem is almost always the USE of a thick 'doughnut' gasket rather than a std 3-hole sheet gasket. Due to the design of the Pantera exhaust system hanger support plus the wt of the assembly, there is considerable force directed back against the header flange. This force along with heat & road vibration eventually destroys the crushable doughnuts. But due to its thinness, a sheet gasket allows the force to go thru it without collapsing. Of course, sheet gaskets won't compensate for much mis-alignment nor grossly non-flat surfaces as well as a doughnut, so you takes your choices...My best guess.

Thanks for both your replies. This is exactly what I was thinking. So I removed
the muffler/tailpipe and found a disintegrated gasket but the flanged end of the tube is almost gone too. A little tab of about 1/2 inch is left. The rest is gone. So it looks like new mufflers will be needed. Not what I had wanted but Oh well.
The other side seems nice and tight. Should I just replace the one side? These area Hall big bore mufflers connected to big bore headers. I like the sound they make. Thanks
for your help. This board is great.