RKL, I changed ours last year in our 02 Journey DL 36GD. I thought It might have gotten wet but that proved not to be a problem. I paid in the area of $65 at the local freightliner shop. I don't remember removeing any other components in the area. It is a one piece canister. It was not difficult, just the usual laying on the back to access it from the bottom with the related dirt in the eyes and the cut fingers etc. It is held into a saddle with two big clamps that go around the body and attached at each end to rubber tubes that are held by large hose clamps.
Hope this helps, Bob