Not sure if this is the right forum for this, but here goes.
I've got the clutch judder on my '02 wrx sedan. I know
that Subaru will fix this under warranty. But which warranty?
The 3yr/36000 mile new car warranty, or the 50000 mile
power train warranty? I just passed the 3 year mark in
May, so I'm wondering if this is still covered.

Unfortunately they will only do this under the 3/36. If you have passed this period it won't be covered any more.

I had mine replaced a couple months ago and they told me it was covered under the power train warranty.

I bought my car used and I'm not sure exactly when the first owner purchased it, but I am pretty sure it was past the 3yr mark. It was still under 36,000 so he may have just made a mistake when he told me what warranty it was covered under. Either way, if you have them take a look at it they should tell you if it's covered or not.

Is this process covered under warranty if the car is modified? I have a TurboXS turboback exhaust system, a TurboXS uppipe, a UTEC, and all the accessories that come along with the UTEC. So, if my car started to suffer from clutch shudder, would it be warrantied?

I would call up a dealer and tell them your circumstance. This is a very common issue and so maybe at first it didn't seem like much, and now by the time it really starts to be annoying the warranty runs out. Some dealers will do the work and some will hassle you. If you are still under the 36k and barely over the 3 years then you have a pretty strong argument.

Is this process covered under warranty if the car is modified? I have a TurboXS turboback exhaust system, a TurboXS uppipe, a UTEC, and all the accessories that come along with the UTEC. So, if my car started to suffer from clutch shudder, would it be warrantied?

More power = More strain on the drivetrain. They may help you out since you have not worked on the clutch, however, they could draw up some reason that your mods had an effect and then decline any work under warranty. Best to call a few dealers in the area and speak to head of service dept.

I would call up a dealer and tell them your circumstance. This is a very common issue and so maybe at first it didn't seem like much, and now by the time it really starts to be annoying the warranty runs out. Some dealers will do the work and some will hassle you. If you are still under the 36k and barely over the 3 years then you have a pretty strong argument.

Is it covered under the extended warranty. I have the gold extended warranty, which basically covers everything.

Is it covered under the extended warranty. I have the gold extended warranty, which basically covers everything.

Not 100% sure. Though I ask'll around and check my sources for you.