I just did this job on my '99 Holiday Rambler Endeavor 37 CDS4.
It's a big job, and a real bear. We pulled that steel tank off the top of the radiator first, opening it up quite a bit. We had to un-bolt the shroud from the radiator/intercooler to get it out. Radiator and intercooler came out in one piece.
Putting it back in: Lay your fan shroud in there against the engine as far as you can. Then(with two people), put the bottom of the radiator in first, and try to get the bottom bolts lined up(the two on the bottom that connect to the frame.
After you get that in place, you need to hook up as much of the plumbing as possible, because after you put that tank on top, access is limited. Bolt the fan shroud to the intercooler/radiator assembly and connect those rods on the top to the frame.
Open the bleed valve and fill with coolant. As long as you've got the radiator out, I will throw this out there. I wanted to replace my original 21 year old fan because it has some chunks missing out of it(small chunks). I found a company out of Oregon called "source RV". You can google it. But they sell a fan for $600 that is supposed to give you 1MPG better fuel economy, 50% quieter, and free up 32HP to the wheels. I haven't tried mine yet but as soon as I get it back I will know more.
Hope this helps!
