Here are some pictures of old trees I've seen in central Florida. I'm not sure the age of the trees, but they seem to be pretty common near the coast (both in Brevard and Manatee counties). I wonder what variety some of the very old ones must be. Reasoner's nursery in Bradenton sold a greater variety of mango than one would expect over 100 years ago (mostly from India, but also some old Florida types like Haden), so there could be some interesting gems hidden in plain sight.
https://archive.org/stream/CAT31295471#page/6/mode/2upIt is nice to see these giant trees, some larger than the local live oaks, laden with fruit. It seems like a lot of the local big trees only produce fruit every 2 or 3 years, but when they do it's a large crop.