I had Dynatec longtube's on my 2000 Z28 and they had nice thick flanges and never leaked. what I had was a problem with driveways they hung kinda low and the car was only lowered an inch and a half, I don't see that being a problem in an H2. the Dynatec headers were a top quality header and flowed like a MoFo. the engine was a 382 stroker and extensivley modifyed ,how they work on a stock motor I can't say .for a heavy truck I would want a header that would boost low end torque . good luck and get them cermic coated ,you will be glad you did in the long run .
