I can think of a few things that could contribute to the Danky smell
Mould grown from water trapped in the AC/Heater ducts or
Under the wiper Arms there is a sheild, under that sheild is a valley. It may be blocked where the water is supposed to run off.
Mould may be growing in there and smell comming through the air vents. My old 32 had a nice fungus growing in there
Stags have sunroofs - damp seeping into hood lining ?
Perhpas even under the centre console (carpet).