I am sure that this is an old, old topic, and has already been much discussed, but I honestly didn't find anything in the Archives to match. I have a1969 1800S and want to use some 1972 Volvo ATS factory accessory "mag" wheels. This means going from a 4.5 inch bolt pattern to a smaller 4.25 inch bolt pattern. I already have a rear end from a 1973 automatic 1800ES available, which should be a straight swap The 1969 1800S was the first with "real" dual (triangle) brake circuits, not just separate front and back circuits, and 2 rear proportioning valves, so I don't see a problem there. What I need advice, or info on is the front brake rotors and hubs. Do I look for 2 1800E disc rotors, or do I need the whole spindle(s), complete with the brake components? Is having my original 4.5 inch rotors welded and redrilled for 4.25 inch spacing a serious option, that is assuming I could find a shop to do the job, and do it with my life in mind!? So, newer 1970-on rotors will fit on older cars, or need the spindles, too? I'm assuming that 140 series disc brake set ups are totally incompatible.