1984–1998M6 Classic
The original body: 0.72× standard finder, selective TTL exposure metering and a mechanical shutter. It does not meter flash TTL. The limited M6J and later 0.85× finder models are special Classic-era variants.
1998–2002M6 TTL
The next generation added TTL flash metering, a larger shutter-speed dial and a slightly taller body. Finder magnifications included 0.72× and 0.85×, with 0.58× added later.
2022–presentM6 reissue
Leica brought the design back with brass top and bottom covers, updated finder coatings and a 0.72× viewfinder. It retains manual exposure and a mechanical shutter; its 575 g weight is specified without the battery. It is a modern reissue, not the original 1984 body.