The original exhaust manifolds on the Javelin had EGR provisions, which are these tubes that go deep into the exhaust port in the head. The PO had taken off the outside components and very poorly plugged them with a variety of screws and bolts (this was likely done in about 1974…). On top of that, the passenger manifold (shown) has a heat riser butterfly valve on it (rusted shut). Below is the replacement, a set of 1970-1971 AMC high-flow, non-emissions manifolds. These are the best flowing you can get on the dog-leg heads. They went right on with new hardware and no gaskets (which is how AMC’s were designed and built).
