The plastic filter came in mid 2002, so early TDI's have an aluminium canister style filter that is a throw away item.
The later style black plastic canister was introduced mid 2002 onwards and uses a paper cartidge filter and also as the plastic drain screw which is HIGHLY likely to break when you attempt to undo it, you must undo it to remove the filter end cap which allows the paper element filter to be removed and replaced.
The plastic screw is not available as a replacement item, you have to buy the entire filter housing assembly as around £120 including the vat.
However I manufacture an aluminium drain screw which is a drop in replacement for the plastic screw. I highly recomend that you purchase an aluminium drain screw BEFORE you attempt to change the filter if you have the latter style filter housing.
I have had to ship out so many aluminium drain screws on quick (read expensive) delivery services because the plastic screw broke and there is diesel dripping from the filter housing, and at £1.75 a litre that is not a good position to be in.
The Aluminium drain screw is £23 with £5 delivery, drop me a PM if you need one, I have stock
Please don't take this as a 'sale pitch', just a few words of warning as I've been party to helping so many A2OC members out when the plastic screw has broken (which is very likely as its been soaked in diesel for the last 20 years which over time makes the plastic very brittle).
Cheers,
Paul