The Dead Vault apparently has tape dating one of these shows to 3/24/70, which circulates among collectors. But they took place the 22nd and 23rd. One of the reviews at Deadsources explicitly places the Dead on Sunday and Monday nights. Pete Lavezzoli has found some eyewitnesses to confirm, and one of them who attended both shows says the GD shows were on the Sunday night, i.e., 3/22/70.

lostlivedead: Grateful Dead/Jerry Garcia Tour Itinerary March 1970

lostlivedead: March 24, 1970, Pirate's World, Dania, FL (Truckin')

deadsources: March 22-23, 1970: Pirate's World, Dania, Florida