I just spent 2 hours fighting with replacing the air filter on our 2004 Revolution XC chassis. This is the sixth time and it does not get any easier. My mobile lube guy who was helping told me he has always seen a sleeve that the upper part of the filter fits into then goes into the air handler/box. The flexible hose is next to impossible to get on the filter due to the angle of the filter, but a sleeve would make all the difference. I have tried to find the 2004 Freightliner XC chassis manual on the Freightliner website, RV Library, all over the internet but only find every other manual and maintenance guide for this chassis. I am trying to find a parts list or manual that will identify that sleeve part so I can get one. Any help is greatly appreciated.