This is a integrated intake / exhaust manifold found on the later MGBs with catalytic convertors.  The early type of manifolds (1975-1978) are prone to cracking over time due to heat and from flexing due to engine and exhaust system movement.

MG rectified this fault in the original design by issuing a revised manifold for the 1979-1980 model years.  This manifold has a distinct horse shoe shaped cast reinforcing rib prior to the catalytic convertor flange. 

Our refurbished late MGB manifolds are shot blasted, inspected for cracks and warping, and then given a coat of high temperature cast iron colored paint to gaurd against surface corrosion.

December 2012:  One reinforced manifold remaining in stock - ready to ship.