What engines fit? and what are the implications?

[Cviji]

Well i've got an Audi A6 which has a failed oil pump, broken turbo and likely engine damage.

Looking for options really, the 2.0TDI engines are available but just looking whether there are any cheaper lumps that will drop in easier, is it only audi codes from 2005 onwards that will fit?

Also, is the gearbox/clutch/flywheel specific to the 2.0TDI?

Any help would be great.

Thanks
Tom