Hi Glaser,
I have never come across anything that looks like your photo
The book I have is for 3 speed types SL3s and SM3s
From your photo yours is more like the 4 speed?
??
Some Moss boxes are remarkably similar to Sturmey Archer externally
BUT they do not have a crash second gear, the gears are constant mesh and the engagement is done with a sliding dog
I think I finally have all the bits to rebuild the one for my Chater Lea, I had to have some gears made and have the mainshaft ground, and the output sleeve (gear is splined on) spark eroded and a bush fitted
Hope the photos attached are of some help?
Regards
John