The 3000 mark III was the last of the 'Big Healeys'. Introduced in late 1963 the 2912cc engine developed 148bhp. The 3000 mark III was only available in a four-seater convertible. The car featured a new wood veneer facia, improved instrumentation and switchgear as well as a new centre console. Leather trim was an optional extra.

The later 1964 Phase II model had some new features such as a new rear axle and suspension, incorporating radius arms, and this gave better handling. Most of the 17,712 3000 mark III's contributed to the North American market, with just over 15,000 making their way over there. By 1968 more stringent safety and emissions standards in the USA meant that the 3000 was discontinued. The final one to be built that year was for the home market.