dry top boxes ?
There are probably some guides around. Maybe on Dulfy?
They have definite spawn points but not every spawn point gets a chest each storm. Pay attention to map chat, kind people will shout out locations, especially if you “seed” the chat by noting where you just found a chest.
As Donari says, the chest spawn points are all fixed, but they don’t spawn in each spot every sandstorm. Chest hunters by now know where the usual spots are and generally check popular “clusters” whenever there’s a sandstorm. Usually players will call out in map chat where chests can be found too.
The two best areas I’ve found are mainly in Prospect Valley and around Crash Site 2.
Oh, one other trick: Press your CTRL key down as you run around, so you can highlight yellow item names. It may depend on your settings, but I can spot a chest over by the Inquest mine entrance after running a very short way towards it from the waypoint. “Buried Locked Chest” is a nice long line of yellow letters.
If you’ve re-assigned your show yellow names button from the default CTRL, use the one you’ve set, obviously.