I have an 02 workhorse chassis and the front rotors are cracked. In looking at doing the brake job myself, I noticed some sort of oil reservior on the center axel. I've never encountered this before, so just how difficult is this to do? Do I need some special tools to remove the reservior and seals? Any help would be greatfully appreciated. Depending on how involved this project is will determine if I do it or spend $$$$ for someone else to do it. Thanks.