Update – Many thanks for the eLearn info, some good information here and offers a way to go.
I started work on this job last weekend, I have the van on blocks on my driveway. I can faithfully report that it would be impossible to replace the rusty pipes on a rusty 2006 Ducato with the rack in situ... So onto plan B remove the rack, something of a major job this, both wheels off, both track rods off, both roll bar ties off, steering wheel linkage assembly off... the list goes on and on... Then you have to get the four rack fixing bolts out... several hours later 3 are out and one needs grinding off... after many hours laying under the van in cold puddles with the rain and snow coming down... Eventually managed to wrestle and wriggle the rack out of the van via the passenger side. What an horrible job this has been and its only half done. So just now I have the van on blocks and out of use and the rack is in my shed. I work during the week, and with some 3 inches of snow on the ground its way too cold to work on the rack in my shed by the time I get home. Maybe next weekend it will thaw a bit and just maybe I can get the pipes off and the new ones on, and I also need to somehow remove the cut off bolt from the rack. I have seen on eBay a reconditioned rack, so I might just go for that... more next week.