A door built or installed around 1980 was engineered for a mild climate load, and the panels held up fine under that - Florida's mild temperate band (per federal climate data) isn't putting stress cracks in steel the way freeze-thaw regions do. What fails here is mechanical, not weather-driven: bottom panels take the brunt of lawn equipment, trailer mirrors, and the occasional backed-into corner, and on a 40-plus-year-old door, that bottom section is often the only part anyone's ever touched. The rest of the door - top sections, the track it rides in - is original to a build era when panel widths and hinge spacing weren't standardized the way they are now. Order the wrong width panel for a house this age and it won't seat against the original track without shimming, and now you've got two problems instead of one.
This is also a smaller, tighter market than the wider service area - about 2,153 households here - so there isn't a high-volume parts counter nearby. We bring the match with us rather than sourcing it after we've already opened the door up.