******************************************** has some easy to use part diagrams: [Edit: I should have checked the links above, everybody else already posted the link to them
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Porsche Boxster Parts
And when there are differences between base and S, or year differences, it will tell you.
Here is the diagram for that part:
Rear Axle Side Section Bracket
It looks like there are different versions for tip and manual, but not between 5 and 6 speed. The part ending in 301 looks like it is the one you need.
Woody will know and make sure you get the right one.