Tensioner Pulley Replacement?

I ordered a new tensioner pulley from http://www.rockauto.com and I'm have trouble figuring out how to take the tensioner pulley (http://www.flickr.com/photos/22325144@N02/2300865194/) off of my 1999 Chevy Prizm. The bolt in the center of the pulley has an unfamiliar head, so I'm wondering if there is a bolt near the pulley that I need to loosen?

I forget the exact bolt for this vehicle but chevrolet uses a female torx socket for some pulleys. Look at a set at the parts store and you should be able to pick out what you need.

Hey, thanks for the help. I think you're right it looks like a external torx socket, I think an E18 which is one size bigger that the set of 7 external/female torx sockets I bought at Sears.

If you can't find one sk makes one around $12.00 and elora makes one around $13.00 www.bloomertool.com
Do a search My tool store sells SK by the individual sockets.

I decided to go with http://www.snapon.com :


SLE180A
Socket, Shallow, TORX, E18

$17 with tax for a single socket, ouch, at least the shipping is free. I see that SK seems to have a good rep, is that what you use? (I've been using Craftsman, fine for me).

I usually buy used if I can find them. I buy a lot from http://www.ntxtools.com/ OTC and SK I've always had good luck with SK. I had a 1984 ford I was changing a head gasket on and broke 3-15mm Craftsman sockets I upgraded at that time with Matco and Mac impacts with a few Snap-on impacts.
Chevy and Ford are using Torx Plus and Torx Plus Tamper at this time. NTX sells just the bits if you have holders otherwise they have OTC and SK. The Pickups started in 1999.
The Elora socket is warranted and is chrome is why I suggested this one.

Make that an E20 socket that I needed, now I just need the time to swap the tensioner pulley.