Most of the area around here - 91 named communities across the wider region - still runs mostly 1960s and 70s housing stock, which means replacement parts for original hardware aren't always sitting on a shelf. A torsion spring sized for an older track isn't universal, and if your opener is original to a 1967 build, the mounting bracket pattern may not match what current openers ship with, which adds a bracket swap to the job.
Headroom is the other recurring issue on houses from this era: some Spotswood garages were built with less clearance above the door opening than current opener hardware wants, so a low-headroom kit or a repositioned opener rail sometimes has to go into the estimate before we can give a final number.
Winters here run cold enough that steel contracts and rubber seals stiffen, so a door installed without attention to weatherstripping tolerance can whistle or bind by the second season. It's a detail that gets missed when a job is priced fast.