G-Rookie,

While the engine shown is a SIMJET, the mounting system is not. I appears to be of custom manufacture and utilized a pair of GATES screw type clamps.

This type of mount is easily duplicated from an aluminum C channel and a pair of the GATES hose clamps as shown. The C channel is screwed down to the airframe mounting surface the engine inserted and the clamps tighetened.

I'm sure there are pre-fabricated mounts available as well.