Dual Dutra Duals...
The current casting now has larger mounting "ears" which allows it to be machined and used on the rear three cylinders.
Note that the tabs are "mirror images" so the older version of the casting could never be used on the rear three cylinders.
As with most things, doing this change created some new issues. The wider mounting tabs will now interfer with a casted-in "chunk" of iron at the top of the cylinder block. We now have one additional process step of grinding this material away so the manifold will mount flush.
One other solution is to cut this extra piece of "dead weight" off the engine block. (Close-up view #2)
Issue #2 is the limited starter clearance this set-up has. A good chunk of material must be removed in order to mount a standard Chrysler starter. A later "mini-starter" clears but the pipe will run right over the top of it. These is some air space underneath but it is a good idea to use a heat shield to protect the starter.
I worked -up a nice set of 2 1/4 pipes which fit nicely under the Hypaer-Pak intake. Both pipes went to a Flowmaster "Y" pipe and then out from under the car with a single 2 1/2 pipe. The parts needed were ordered from Summit for under $100.00 (a"Y" pipe, 3 "U" bends and a glasspak) This is what I came up with. One "trick" I used to get everything installed correctly was to heat and bend some PVC pipe into the shape I needed for "fit checks". Once fitted, I would use this to guide my cuts on the metal pipes. The set-up is light, has good under-chassis clearance and flows well. The car really has a roar to it! DD
NOTE That this set-up has no choke stove "pockit" and no intake manifold heat.