I had a closer look at the swing and I found the text Profab on the crossmember, just in front of the rear wheel. The text is in thick, large letters and is pressed from the inside-out
After some searching (also on this forum), I've found out that Profab is a wellknown and highly sought after swingarm for the HL500. Anyway.. allthough my swingarm looks a bit different, I still believe that it is a genuine Profab swing.
HL500 swingarm:

My swingarm:


Does anybody have an idea where I can find a chainguide for this swingarm? Profab itself does not have a website but maybe someone knows where to get parts for these swingarms. An alternative is to modify an existing chainguide (e.g from a KTM EXC or so) by only using the nylon part and folding a thick aluminum plate around it that fits my swingarm.
Erwin