We stock the common torsion spring sizes and standard-width cable that cover most doors from DeSoto's build era, along with rollers, hinges, and the usual opener drive components - gears, sprockets, belts. What we don't carry on the truck is anything custom: a specialty panel width, an obsolete opener model no longer made, or hardware for a door that's been modified from its original setup. On those, we'll tell you honestly if it's a special-order part and what that means for timing, rather than pretending we have it in the truck.
One limitation worth saying plainly: if a door is old enough and damaged enough that a fix means chasing down parts for a system nobody makes anymore, replacement is usually the better call, and we'll say so instead of running up a repair bill on a door that's on its way out anyway.