The final version of the GT6 was produced between 1970 and 1973 with 13,042 units built. It had a mid-life upgrade with a conversion to using the Spitfire MkIV suspension being introduced. In the U.S. the familiar problem of less power again hurt performance. The compression ratio was reduced from 9.5:1 of the Mk 1, to 9.25:1 in the Mk 2 and 8:1 in the Mk 3 with a result that only 90BHP was produced in early models (1971) and an even lower result of 79BHP (1972-73). Home market cars continued to enjoy 104BHP.