its not an easy job either way you do it , it is easier with the down tube out , the bolts at the top need to come ose and the two bolts at the manifold , which are no fun because they are usually rusted to hell, the clamp at the egr cooler and the pipe comes out , put your block off in and reasemble , the hard part is geting the bolts out , i usually cut them with a cut off whel and get new instead of fight them