When I transfered the roof rack from my 1986 to my 1990 740 there was no rust whatsoever under the feet of the rack. It makes a huge difference to check and retighten the feet frequently. In my experience, the rubber pads do a good job of preventing water getting into the holes. On my 1990, I used some black caulk and galvanized screws to attach the old rack to the new car. This cost me about $4.00 and the nerve to put 8 screws through my car roof. It held up very well over the 1.5 years I owned the car, and I used the rack a *LOT* I secured plywood, sheetrock, and misc lumber to it on many ocassions. I did checked its strength continuously and found it to hold up well. I never had any problems.

The Volvo Dealer wanted $250.00 to install a the rack that I ready owned onto my 1990.
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Volvo #6: all wagons.... 1972 145S, 1976 245 DL, 1983 245 GL, 1986 740 GLE, 1990 740 GL, now a 1995 940...