[63gpman]

Being from the rust belt I have seen this a few times on these Grand Prix or Cutlass cars. Most just go to the junk yard for scrap. There should be a ton of these in the southern states where rust is not as much of a problem and I guess that would be my advice if you decide to fix it.

[3 Chiefs]

This is talked about a lot on the w-body forum. When GM transitioned from a mono-leaf composite spring to the coil over system, they beefed up the upper wheel house to accommodate the weight of the vehicle. I think doubling up on the steel left two layers that hold moisture and when the seem sealer falls out it starts to rust.
I have been doing extensive rust repair on my 94 GP but it is in different places than yours. These fwd Grand Prixs are disappearing everyday. I hope you do not junk the car for this.
If it were me I would go to a pull and pay lot armed with a battery operated reciprocating saw and cut out the section you need. Not all GPs will be rusty there. I have been able to find lots of rust free sheet metal here in Kentucky and I bet you can too where you live.
You will have to remove some interior for the welding in process whether you do that part or pay someone else to do it. I know it sounds like a lot of work but it is do able.
On the w-body forum you will find many topics on this repair.
Just don't junk the old car, she needs your help now.

Paul

[3 Chiefs]

Also I cannot be sure that the wheel housing would be the same but there are other w-bodys out there besides the Grand Prix.
You may be able to source that part from an Impala, Regal, Cutlass, Monte Carlo and Lumina. Obviously do some checking first but those are all cars built on the W body platform.

Good luck.

[1969GiPper]

Just by chance I checked Craigslist in my area and "bingo", there was a guy parting out a 2003 G/P. Ad even had a picture showing a rust free right rear wheelhouse. Only $20.00. Had a buddy of mine at GM check and the 2003 part should work on my 1997. He was about 40 miles away and I went to see the car armed with a sawsall and a grinder/cut-off wheel. Before I had a chance to roll up my sleeves the guy took my saw and climbed in the trunk and started cutting away. Probably took about 45 minutes to get the wheelhouse out. As for me I hardly did anything. The guy even carried the part out to my car. Gave him the $20.00 plus an extra $10.00 for his effort. Next, finding a body shop to do the job. Did notice that that that 2003 G/P had a lot more splash shields in the wheelhouse then my 97.

[3 Chiefs]

Great, that's a good deal. On that type of repair, I would overlap the joint for a easy fit. Cut the old bad stuff out then have someone hold the replacement section up underneath and trace it out. After it is removed, add 1 inch around the mark and that should be good. Make sure they put seem sealer over the weld inside and out so hopefully the rust issue never returns.
I am glad you are fixing it.


Paul

[1969GiPper]

Stopped by several body shops to get prices for doing the repair. None were interested. The last place gave me the name of someone that might do it so I paid him a visit. He took a good hard look at the situation and said that installing even part of the wheelhouse I brought with me would be nearly impossible. That he had repaired a Buick Century with the same problem (only on the left side) by fabricating a part. Gave him the go-ahead and a few days later got the car back repaired. So far I'm satisfied.