Oh for crying out loud the owner of the TT used a film camera to take the photo and at some point (most likely the scanning of the print) it was reversed. This is a simple case of a photographic screw up.
On the other hand, Rowe/AMI made thousands of jukeboxes with this mechanism. The cartridge is mounted backwards in the tonearm, the stylus points toward the back. This is a rather dirty example.
Typically 5 grams, but they'll go lighter. That isn't a dust shadow, it's a little raised dome so that the tonearm wires can fit between the arm and the cartridge mount. With the cartridge backwards the terminals are on the leading edge of the tonearm. Earlier mechanisms used a mechanical microswitch to trip the mechanism at the end of the record. Later units have a magnetic reed switch. With a reed switch they'll track down to 2 grams with the right cartridge. The mechanical switch puts some side-pressure on the arm towards the end of the record so it skips below about 3 grams. Stock cartridge is a Shure M44, designed for 5 grams. The DJ cartridges made today are good replacements with similar specs.
You don't want to go too light, otherwise the records skip during bar fights when someone whacks the jukebox with a beer bottle.