Review on Dorman 674-703: Front Catalytic Converter with Exhaust Manifold for Chevy/GMC/Hummer Models - Non-CARB Compliant by Edwin White

The previous comments on this manifold with clearance issues on the Hummer h3s are correct. I had to spend 3 hours grinding the gearbox housing to get the manifold to fit properly. Totally pissed about it. I have always used Dorman products and this was the first time I had any issues with this brand. The manifold also came with a random exhaust manifold gasket for the 4 cylinder engine and not the correct one for the 3.5 5 cylinder engine. I would choose a different brand if you don't want to spend hours grinding. Don't be like me and ignore the bad reviews, they are correct.