As far as i know?? they may still be making a similar version??
Looks as if there is an old one on this site,
https://www.gunstar.co.uk/Air-rifles-for-sale/Side-Lever/Diana/ADI/Air-Guns
Looks as if there is an old one on this site,
https://www.gunstar.co.uk/Air-rifles-for-sale/Side-Lever/Diana/ADI/Air-Guns