td gearbox

[DirtyDave]

rite then i've got a horrible rotating noise coming from the nsf of my car. i thougt it was the drive-shafts but now am led to believe the diff in the box could be knackered. the n/s drive shaft is moving out of the box by about 5mm. i've changed both shafts for recon ones. Is the gearbox hard to change? how long will it take? are the td box's different?

Any help would be brill

Dave