driveshaft/gearbox help!

[jono172sport]

hi guys
the driveshaft has been nocking realy bad on my 2001 172 sport, its fine if you drive straight or turn right just really bad (like shakes the whole car vibration bad) if you turn left the slightest bit so i bought a n/s shaft but now its nocking all the time in all directions also when the car is jacked up if you spin the n/s wheel you can see the shock and wheel moving up and down slowly while spinning like the shaft or gearbox is moving it up and down
anybody have any ideas? could i need a new gearbox?

any advice apprecitaed
jono

 

[jono172sport]

anyone?
just been out to it if you jack it up and spin nearside wheel you can hear like a knocking noise coming from where the shaft goes into the box and if you put your hand on top of the box while spinning the wheel you can also feel it nocking the drive shafts on it are megan 1.5dci drive shafts i believe they have the same splines each end just a little bit shorter?