Unfortunately, The guy I knew that did the conversion used someone elses upgrade made for the nexus. I'd still bet that the century torque tube will work. The only thing I'd be concerned about is the spacer that sets the space between the two bearings on the shaft that comes off the main gear. I have used the Century tail boom on my Nexus as well as the entire tail gearbox from a century heli. It was all interchangeable. You might give century a call. They may have a TT kit for the Nexus. They used to have other upgrades as well.
Good Luck, Sorry I couldn't help more.