Doors from the late 1980s in this area typically use standard-width galvanized track and extension spring hardware, both of which we carry on the truck as regular stock - this isn't specialty gear, it's what most of the service area still runs. Nylon rollers, hanger brackets, and the sheave pulleys that extension-spring systems use for cable routing are also stock items.
Where we run into a wait is on anything original to a 1987-era door that the manufacturer has since discontinued - a specific hinge pattern or a non-standard track radius on an older custom install. That's uncommon, but when it happens we'll tell you up front rather than guess at a fix date. Most off-track calls in a neighborhood built out in this window don't hit that wall; the fix is track, rollers, and a realignment, all parts we already have with us.