Yep - all the signs are pointing to the 97mm ones being fine. That part number points to 97mm and I've read that Audi started using longer ones because they do a better job of heating the fuel, which apparently reduces emissions.
It sounds like a few other people have been worried about the longer ones, but I found a thread on UK MKIVs saying they fitted them in the ARL without any problems, so I'll fit them now and cross my fingers.
The ones that came out were NGK ones. As far as I know, they've not been changed, although I bought the car after the interval where they could have been changed, so who knows? They look a bit sad and coked up, so doubtless needed changing anyway.
Here's a photo with the part number:
When I find my multimeter I'll check them for resistance. The car has been pretty sluggish starting lately but no codes and only the occasional glow plug light.
I'm just looking forward to getting it done - I bought these plugs in March 2021, so that gives you a good idea of how worried I've been about snapping them.
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