Leica has always called its f/1.4 lenses "SUMMILUX," regardless of focal length or optical design. Thus SUMMILUX is a meaningless trademark, not any indicator of lens age, quality or design. All these lenses are sold as "SUMMILUX" lenses.
1961 ~ 1990: 35mm f/1.4 SUMMILUX-M (11 870)
The first 35mm f/1.4 SUMMILUX-M (11 870) had 7 spherical elements in 5 groups. It's a conventional double-Gauss design.
It weighs 245g and is only 38mm long.
In the beginning, it also came in a version with additional finder optics (11 871) for use on the M3.
By itself, this first 35/1.4 focuses to 1m, and with the M3 reducing optics, focuses to 0.65m.
The first version, up to serial 2,166,700, used a bizarre 41mm filter, then was changed to use series VII instead. Neither size is easy to find today.
The first version used the 12 586 hood, and the latter uses the 12 504 hood.
It has come in silver and in black.
An optical advantage of this first version 35mm f/1.4 is that its mostly symmetrical design produces no distortion, unlike the slightly stronger distortion (bending of straight lines) of the newer aspherical versions.
This first version is pretty soft at f/1.4 and can't use easy-to-find filters, which limits its appeal, but its lack of distortion and having the same sharpness as the current lenses stopped down can make it a winner.