vnt17 or 20

Hi Guys OK. Let me extend my question a little bit further then. We have 1 VNT17 and 1 VNT20 in our hands and we would like to build a hybrid VNT17/20 unit with them. Which parts we must use from which unit, for instance rotor of VNT17 and the main body of VNT20 etc. ? At which points we must...