Hi Raymond.
The Aeroxraft lines up perfectly with the 550 - but with the 450, yo need to use some regular nuts and bolts (not the very wide plastic jobbies that come with it) then it 'just' fits as the holes on the mounts on the landing gear align with the holes that are in-between the 450 arms. Just needed a few decent sized washers on each end and hey presto - it fits a treat
It isn't cheap - but it's a nice bit of kit and you can move the lipo / gimbal on the rails to balance it all.
Just had another go with it in the park - i'll try and upload something to vimeo if it's any good!