We come out from our Katy base, measure the actual opening, and size springs to the door you're putting in - not the one that's coming down. For most Four Corners jobs that means replacing door, springs, and rollers together, since the original hardware is past the point where mixing new parts with 20-year-old torsion springs makes sense. If your opener is the original chain-drive unit, we'll tell you honestly whether it's worth keeping; often it isn't, given the age. One limitation worth saying plainly: we don't stock every custom panel style on the truck, so a specialty design may mean a short order lead time before install day. We'll tell you that up front, not after we've already pulled the old door down.