The yellow card says:
Gustav Flink, Aamaal, Sweden, most famous as a producer of power-up parts for Husqvarna Silverpilen (Silver Arrow). Produced his own engine, and in the end a complete motorcycle. The constuction is not like anything......blitzflash...... fueltank integrated in the frame. The exhaust is also a part of the frame, the volume is calculated, even the footpegbrackets is volume-calculated. Only made in a small number. Owner Bengt Karlstrom, Sala, Sweden.
Probably some spelling errors as english nor swedish is my native language, but the contents are correct.
Flink made a lot of tune-up parts for Husqvarna before the factory went in heavily in MX, but the bikes is wery rare.