I have a 20 year old GBM with a 454 eng and I have spent $13,000 since I bought it 11 years ago for repairs, mods and general maintainance over 85,000 miles of travel. This includes all fluid changes, circuit boards for refer, levelers, WH and genset, and every thing that broke. I spent a small fortune on this IFS front end. I would say between the front end repairs and upgrades,headers and othe major mods made up half of the total. I have done most of the work myself except for front end and headers. If you do not have major repairs or mods ( your MH will be newer) your costs doing the work your self you will probably spend $5000 to $6000 over a 10 year period based on my experience.