I found this under the carpet in the rear hatch area. Not sure if this is 928 part or not. It's made out of thick rubber. Any ideas?

 

one of these floating around in my hatch too, always wondered what it's for.

 

Should be glued to the underside of your battery box cover over the battery posts to prevent battery shorting out to the body.

 

There are three of them placed on the area below the spare tyre to stop it rattling.

 

Or it may be one of the three rubber pads (used to be) glued to the spare tire well to prevent the spare tire and tire well floor from scratching each other up.

 

I almost wish none of you knew what that part was , because armed with your suggestions I decided to look at the battery to see which of the three was missing. It was easy enough to determine it was the one on top of the neg post but then I decided to completely remove the battery and clean the box and all the trunk area. Now it's 3:00 and I have a half finished project and a bunch more questions. Thanks guys ;-)

 

these rubber pieces do not go into the battery box .

they are for the spare tire rim edges so they wont damage the floor and otherwise make noise.
there should be three of them glued to the floor of the spare tire well as Roger and Rob have stated.
The bolt and metal plate hold the spare to the floor

 

So what is the hole for ?, does it locate on something , ie orientation ?

 

It is a speed hole.

 

If the battery is properly sized and properly clamped, it will NOT hit the battery box lid. There are three of these pads on which the spare rests.
Dave

 

At the risk of being really pedantic, some of those factory pads have no hole, some have a round hole and some have a D-shaped hole. Not sure which years got which shape. If you order 911 201 259 00 new, you get D-shaped holes.

 

same reason for holes in the White castle hamburger - weight savings!