UKPassats

Well after 312k my box has sprung a leak and sounds noisy as hell im not sure if any of it has to do with a single mass flywheel I fitted 12 months ago.
But im looking at replacements what I have is a 2007 bkp equipped car with a 6 speed manual gearbox code kdn
has anyone fitted a different code gearbox without issue ( plug n play)
or must I only use the same one?

Thanks