The Carrera 7753 replaced the two register 3646 in 1970. The main difference being the 30 minute register at the “3” position and powered by a Valjoux 7730 manual wind movement. All dial are second execution with shorter hour markers. Heuer also offered a wider variety of dial options including those with scales as well and contrasting colours. Case proportions remained unchanged and featured a signed crown, domed plexi and 18mm lugs.