Definitely boge-mullhollands. Was a popular choice in the mid-late 1970s for trials bikes. I still use a set of them for trials on a TY250, but I think the springs on mine might be softer than those. Compared to the plush damping action available from (competition standard) twinshock trials bike shocks nowadays, those shocks have too much high speed compression damping but they are great for trail riding and they are pretty tough and reliable
My Boges are 350mm centre to centre which is good for a TY250. If yours are 350mm that is pretty close to perfect for a M92, but if you are replacing, 360mm would be the go