Hi,
What you have was called the NVMT5 weapon kit.The cage mounting to clamp it to the rear of your day scope sadly disappeared with the demise of Soviet Bazaar.A new version is available but is designed around the D126,which is very different to your NVMT .
Soviet Bazaar also used to produce a sliding mount system to enable proper eye relief to be mantained.
If you have an old scope mount you could cut the base off,and bolt a rear extension to it with a hole to take a bolt that will fit the NVMT.From memory the first ones were 1/4 in machine thread,I think they later went to M5 or M6.
If you elongate the bolt hole and use a washer you will be able to slide the NVMT up behind your dayscope.
Tommorow I will be telling the forum how to build their own nv monocular using a toilet roll and double sided sticky tape.