A4 1.9 TDI 5 Speed Box Questions

Hi all,

So I have an A4 S-line 2005 1.9 TDI which I've had only a short time. Recently, a whining noise has developed which seems to be coming from the box itself. The whining is in time with the engine speed in all gears, but not present when the clutch is depressed. Very recently, 4th gear seems to pop out almost all the time while driving. I have changed the oil & I've made sure there was plenty in it. I think it has been leaking some oil from there & surely over time it has done some damage to it.

My questions are - if I was to get a second hand one from the same model/year, would it be a straight forward swap out or would there be more involved?

I've heard of a 6 speed conversion - does this involve a lot of extra work?

Do any of the previous generation boxes fit (such as the B6)?

Any advice on this would be greatly appreciated.

Cheers,

Chris.