Hey i want to say thank you to every one that has helped me so far with my issue of the P0449 and P0455 codes. Im still having some issues. i have read on some other forums that a vent valve solenoid that is suppose to be for a cavalier will work on the silverado and the cost of the part is cheaper. Has anyone heard that? if so is it true? and if so what year cavalier/engine works with the 06 silverado with the 5.3? Also has anyone found this part some place cheaper than the dealership? if so where and does anyone have a part #? I dont really want to shell out the $150 for the part at the dealership if i could of got it someplce else for cheaper. Again thank you to everyone in advance for your help.