dodge 6 flathead

[johnD400]

I have a 1958 dodge 400  .. replaced  plugs wires point condenser , rebuilt carb etc,   set timing .. ran great at Idle but faltered bad at im guessing about 100 rpm plus . someone told me maybe broken or stuck valve spring . firing on all cylinders .compression on all cyl. right at 120 lbs,    took the exhaust manifold off and discovered a large hole and several cracks in it.  Im hoping this is the problem .  bought a new used manifold . went to install it, but gasket set doesn't fit . Fel pro Part # MS 8009 B     all the local parts store say this is the right part but its not .   Anyone know of correct  part #  ??   Also Im not sure which motor this is   .  251 ??     thanks in advance for any help 

[Dodgeb4ya]

You need the set for the 25" long 251/265 engine.

[Charlie Stephenson]

What is the Engine Code number?