Rug doctor vibra vac age and identification question

[2011hoover700]

Hi I just bought this rug doctor vibra vac as of Saturday and I'm looking to know around how old it is and know more about it.
Here's a few pictures.

 

[adam-aussie-vac]

This looks very similar to the RD4, except it might be a

Dual Motor version, I’m not sure if it uses the 172 mm variations, or the smaller versions