Here's something else we didn't expect. There's no way the right-side header would go in without removing the engine's oil dipstick tube. We tried a mechanic's trick of using hose clamps, a piece of coat hanger, and a slide hammer with gripping pliers to try to extract the tube from above without damaging it, but to no avail. After several tries, we ended up using locking pliers and a hammer, knowing we'd ruin the tube in the process. We ordered up a new dipstick tube from our local Chevy dealer for $37.