The exhaust manifold used on the 1975 Opel Manta, Ascona, and wagon was considered a 'Sprint' manifold. As that final year of US-imported Opels came with fuel injection, they came with an exhaust manifold which had no heat riser (the portion which normally bolts to the underside of a carbureted intake manifold). It is exactly the same manifold otherwise, in terms of fitment to the head and to the downpipe, so it is a direct swap to any non-fuel injected CIH Opel.
The only modification required is the grinding of the triangular protrusion from the top of the exhaust manifold which would otherwise hit the underside of a carbureted intake manifold (alternatively the aluminum intake can be ground away somewhat to lessen the amount of cast iron that needs to be ground from the exhaust manifold).
The naming of the 'Sprint' manifold dates back to late 1967, as this exhaust manifold design was used on the European-spec Opel Rekord 'Sprint'. The Rekord Sprint used a 1.9 litre engine with a special cylinder head (1.9H head to increase compression by about 1/2 point), a pair of 40 DFO downdraft Weber carbs on a special cast aluminum intake manifold, a slightly hotter camshaft, and the aforementioned exhaust manifold. Oh, and the Rekord Sprint also used the 'Opel GT' aluminum valve cover before the Opel GT was in production. All these changes netted an engine rated at 16 ps (metric horsepower, about the same as 15.68 hp) more than a normal 1.9 litre Opel engine with flat-tops. It was essentially a German version of a muscle car, replete with stripes and styled wheels.
Bob