API suspension components

[TM-Frank]

I have here a fork and a shock that are quite exotic to me.
Brand-name is API, since the clickers are labeled in German I suppose the stuff is of German or Austrian manufacture.

Fork: It is an inverted fork with 42mm lower tube diameter, compression damping in the left leg, rebound in the right. The fork has no springs and works with air pressure only. Triple clamps are billet.

Shock: The shock looks a bit weird, too. The spring looks rather weak and the piston shaft is about twice as thick as on a standard shock (I guess around 30mm diameter). It seems to work with adjustable air pressure, too.

These parts are mounted on a KRAMER 450 twostroke (model year around '83) but at least the fork wasn't stock equipment back then.
Can anybody help out with any information (tips, documents etc) about that stuff?

 

[TM-Frank]

Here's what I found out about the parts in the meantime (in case anybody's interested):

These forks and shocks were made by a south German company named Müller Präzisionsdrehteile (which translates as Müller Precision-Lathe-Parts) in the early/mid eighties. The company still exists but nowadays doesn't work for the motorcycle industry anymore.
They supplied KTM and Kramer back then. Later they renamed their suspension parts from API to MDS. The MDS air fork was installed on a early KTM LC4 series that also came to the US market.