Struts

I have an 02 GT with 65K on it. I just found out one of my rear struts is leaking. Should I replace all four or just the back two? What is a good brand to get for replacement. Do I need to worry about the springs or any other parts that may need replaced.

You can get away with just replacing the back two. Gabriel, Monroe and KYB are all good brands.
Just be sure to get the strut that specifically matches the suspension package that you have. Sometimes struts for base model suspensions are a little different in their damping characteristics.

Try to stick with the OEM GM/Delco since the GT and GTP have a tuned GT suspension system with stiffer springs and specially valved struts either GM RPO code FE2 or FE3. At your mileage best to do all four if you can afford it. Check the SPID label located on the back of the trunk lid for the suspension package code. The only other aftermarket strut I would consider is the KYB GR2. Monroes and Gabriels are too generic in nature and fit other GM "W" body cars. Too soft for my taste and you will notice a loss of handling as a result. After about 40K miles they will feel terrible. I use KYB GR2 all around in my GTP. Replaced at 70K miles.

On the strut coil springs just measure the height after the strut is removed and compare against FSM specs. Also, a good idea to replace the upper strut mounts and load bearing assembly. The rears just have a upper strut mount with no load bearing. Use Delco only. Monroe mounts may be noisy after installation.

Is their a big difference between the OEM and the AC Delco struts. The OEM struts run about $35 more than the Delco struts.

The AC Delco and GM OE struts are almost the same and sometimes one in the same. Supposed to meet the OE specs, regardless.

Checkout ZZP. See link below. They have the OE GM struts for $160. Thats is all 4 struts.

Part # 10386996 for front Part # 22227752 for rear.

Click here (http://www.zzperformance.com/grand_prix/products1.php?id=883&catid=138)