This thread has a checklist attached that I made recently before buying a 300Tdi 90.
I ended up with going with one that didn't tick all the boxes and I definitely didn't spend as long poking/hitting the chassis as a should have (hence I am looking at getting the bulkhead outriggers replaced)
From what I have gathered, bulkhead replacement can be quite a big job and it is integral to the structure of the vehicle so you can't get away with too much corrosion to it.