Nice looking Waggy!
BTW - The V-8 did not have exhaust donuts, only the straight 6 engine did. The header pipe has a flair that fits the exhaust manifold. Leak may be a loose connection, exhaust manifold gasket or the emission air pipes blowing into the manifold.
I think I used Remflex exhaust manifold/header gaskets last time and never had a leak issue again.
Steve, Christy, Anna and Scout (Border Collie)
1994 30'11" Excella - rear twin
2009 Dodge 2500, 6 Speed Auto, CTD, Quad Cab, Short Bed
Hensley with adjustable stinger
WBCCI # 3072
AIR # 6035