We just went through this on Dad's P/U. Cronic leak at the connection. Crawled underneath (clamp removed) and had a good look with a jack holding the exhaust system in place and found the pipe was A) bent at the wrong angle and B) pinched by the clamp when Dad over tightened it to quiet the noise.
Solution: I removed the entire pipe and put it on the floor, we heated it up cherry red and bent the riser witha pipe inside, to the correct angle to meet the manifold (This took a couple of shots and may be more due to sag of the manifold than and incorrect bend of the repop exhaust).
Once we had a straight shot to the manifold we heated up the flange area and hammer and dollied it flatter to meet the manifold. (I did this using a spare manifold clamped down and the muffler loosely fitted to the manifold like an anvil. Work great and we had a good looking seal area).
Lastly Do Not over tightened the clamp or it will cause a pucker in the pipe and subsequent leak.
Another hiccup to watch for: when you mount the exhaust, hook the two clamps (front and rear) loosley first the tighten each a bit at a time and check for clearance at the right rear radius too!
Woked for us.
