According to the Parts Catalogue for the'48 to'53 Series 1, it also fits these models from Engine Number 06115161 onwards. It comes with the 4 bolts that fix the assembly to the cylinder head and 4 studs to attach the water flow pipes. It is not the aluminium version, it is a machined steel casting. It's a heavy item - including the 4 bolts and studs it weighs 2070g.