The bike shown has chromed rear stays which were only used on full 531 frames and you can see the 531 fork sticker... not all PX10's had the ornate Nervex lugs and some smooth sided lugs were used.

You can also see the 531 sticker on the down tube which makes me fairly certain the old guy is holding a PX10... the Op's bike might be something completely different so we will await pictures of the real bike.

Identifying Peugeots can be a very difficult task...