metallic ring gasket
The gasket is a metallic ring type that fits in a recesson in the midpipe flange. I used a Walker part# 31332, cost about $4. You'll likely have to scrape out the leftovers from the old gasket with a flat bladed screwdriver. Use some exhaust joint cement or sealer to bed the new ring and some on the opposite flange so you get a good seal once you bolt up and tighten the joint.
Cheers.
