Bosch and Beru are both OEM for that era TDI... I believe one of them licenses the design to the other, and many people mix and match them - most of them successfuly so... NGK may also make plugs for your car, but I wouldn't look at any other brand. (BTW: most of the online vendors will sell them for much less than your friendly local VW dealer or parts store... try boraparts.com idparts.com metalmanparts.com )
Keep in mind that if you have a Check Engine light, it may also be due to corrosion in the glow plug harness rather than a faulty glow plug (check resistance with a digital ohm-meter... should read somewhere between 0.8 and 1.2 ohms)... Also, the light will not go off by itself after you've replaced the plug and will need a scanner to clear it.
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