Complex sentence: The European one that lasted longest was the lorries arm of Ford of Britain, which was eventually sold to Iveco group in 1986, and whose last significant models were the Transcontinental and the Cargo.
Split into simpler sentences: The European one that lasted longest was the lorries arm of Ford of Britain, which became part of the Iveco group in 1986. Ford's last significant European truck models were the Transcontinental and the Cargo.