Complex sentence: From 1953, the bodywork was produced in-house, while the Crosley sourced engines underwent a radical transformation, adopting a new head with gear-driven DOHC, a single Weber carburettor replacing the Dell'Orto.
Split into simpler sentences: From 1953, the bodywork was produced in-house,. Meanwhile the Crosley sourced engines underwent a radical transformation: a new head was fitted with gear-driven DOHC and a single Weber carburettor replacing the Dell'Orto.