JB mentioned in a post that you might get by with inframe overhaul, if that the case I can project a possible figure that might give you an idea of cost. The previous owner of my MH had to have a inframe overhaul a couple of years ago on the 400 Cummins. I got a copy of ticket for reference The charge was just shy of $20K from truck center at Lubbock Texas. I'm sure prices are up but that might give you and idea if that is all needed.
competitive shooter RVer
2006 Gulfstream Friendship G7 8411 400HP Cum.
RM Sterling/'07 Chevy Colorado CrewCab 4x4