sentences:  Besides the larger displacement, other notable mechanical changes were aluminium cylinder heads, an improved chassis frame and a new transmission.The same upgrades were applied to the 1933 model 6C 1750 Gran Sport which, together with the 6C 1900, form the sixth series of the 6C.Alfa Romeo offered the 6C 1900 with an in-house 4-door saloon body, while bespoke coachbuilt body styles included 4-seater cabriolets.