Hi Angela, I'm pleased to assist you. No need to weld this converter on your 2004 Pontiac Grand Prix 6 Cyl 3.8L. They are attached by bolts, which you can reuse the old ones. But, you will need to replace the insulator and the gaskets related to this part. Click on the links below to complete your order at discounted prices while supplies last. I hope this is helpful. Enjoy shopping at CarParts.com! Catalytic converter (49% off) - https://www.carparts.com/catalytic-converter/walker/wk54752?can=CPGG4850_CSQA_20220802 Insulator (60% off) - https://www.carparts.com/details/Pontiac/Grand_Prix/Walker/Exhaust_Insulator/2004/WK35352.html?can=CPGG4850_CSQA_20220802 Exhaust gasket 31605 (29% off) - https://www.carparts.com/details/Pontiac/Grand_Prix/Walker/Exhaust_Gasket/2004/WK31605.html?can=CPGG4850_CSQA_20220802 Exhaust gasket 31578 (53% off) - https://www.carparts.com/details/Pontiac/Grand_Prix/Walker/Exhaust_Gasket/2004/WK31578.html?can=CPGG4850_CSQA_20220802

Hi Alvin, I'm glad to help you out. This item includes the hanger shown in the photo. The mounting hardware and gaskets are sold separately. Take advantage of the sale price and limited stocks for this item. Click this link to order this part: https://www.carparts.com/catalytic-converter/walker/wk54752?can=CPAP3648 I hope this helps. Happy shopping.

Hi Tim, As per checking, this item does not come with bolts/ mounting hardware. We suggest getting those locally through a local auto supply store. They sell them at most auto parts stores.