I think this is a later example of an drop-out mounting SunTour 888 Wide derailleur - probably manufactured by SunTour themselves. Nearly every detail is different from my ‘second style’ example - the knurled nut through which the toggle chain emerges is quite different, the main plate is a different shape, this example has a cable adjuster, the grip pattern for the track nut is radial rather than criss-cross grooves, the pulleys have a slightly different profile, the branding is embossed not an enameled plate etc. etc.. It is hard to see how the same factory could change so many detail between models!
This example is branded ‘SunTour Wide’, this is in modern angular script on the main plate and in rather florid cursive script on the pulley cage plate.
The underlying design remains a version of a Huret Competition - albeit with ‘touring’ dimensions and the top pulley concentric with the sprung pivot. However on this version the sprung pivot is 85mm from the hub axle centre and the pulley cage is 65mm long (both less extreme than my ‘second style’ example).
Note that right up to the mid 1980’s SunTour used this geometry of pulley cage that was 65mm between pulley centres and had the top pulley concentric with the sprung pivot (see all the SunTour V series and derivatives up to and including the 1984 SunTour BL GT black).