I swapped a 1994 Lincoln 4.6 into my 66 Mustang and used 1999 Mustang exhaust manifolds due to space constraints. The right side exhaust has an "oval" opening. I don't seem to find a downpipe to make that connection. What am I missing? The catalytic converter attached at that point and I simply unbolted it when I removed it from the Lincoln so I don't have that old pipe to use. Where do I get a new one. I don't seem to find one on the interweb. thanks