For a neighborhood this age, we carry extension spring kits in the sizes that fit 1970s-era single and double doors, plus the pulley and cable hardware that wears out alongside them - these aren't the parts a shop stocks for a newer torsion-only fleet. We also bring photo-eye safety sensor kits, since a lot of openers from this build era predate the 1993 federal requirement for them and still need a retrofit to meet current code.
We stock torsion conversion hardware too, for the households that decide the extension spring system has reached the end of its useful life. That's a bigger job, so we don't always have everything for it on the first visit - a non-standard torsion bar length or a specific drum size sometimes has to be ordered, and we'll tell you that plainly rather than pretend we can finish in one stop.