Have never done this myself but good luck - the info on this forum is pretty detailed on the job the link thomaspin posted is absolutely terrific.
If you have a reliable parts supply (and I mean reliable) when you have the new rails in your mitts and are able to compare with the rails you take out - then your knowledge of the true position will be confirmed.
I expect by then you will have the confidence to tackle whatever is necessary in this area ;-)
Best of Luck (and keep us posted)
230 TE (W124) 1989 with 153,000 miles on the clock - hoping for at least another 100K