pics of all factory manifolds (you want the C5AE-*):
http://home.alltel.net/bsprowl/ExhaustManifolds/FactoryEx/indexExhaust.html
interchange guide:
http://home.alltel.net/bsprowl/ExhaustInterchange.html
the 1st link nicely shows the difference between the 63-64 version
and the 65-66 version. despite what seems like an acre of space
on the top end of a 66 galaxie, it is comparitvely cramped
on the bottom end.
Bob's site (
http://home.alltel.net/bsprowl/) is a wealth
of information.