It is something how guys beat up and abuse their stuff, butcher and frankenstein it, leave it sit for years, and get the sounds they do. So, it was resurrected for Live 8, and the On an Island project. He was trying a few different things, he picked up the Black Strat, and the crew noticed his demeanor and body language changed, and things really picked up. It was in the line-up for Live 8 rehearsals, but David was using the red Strat. Somewhere along the line, one of the '57 necks got swapped on it, and it still sat around.
Then, it sat on loan in a Hard Rock Cafe somewhere for 10 years, Taylor got it back, and it sat around while David was using his '57 reissues. it was even routed and had a humbucker installed between the mid and bridge pups, but David didn't like the sound, so it was removed and the hole filled in.
It had a pup change and a neck or two, and it has been used in recording Dark Side of the Moon, Wish You Were Here, Animals, and The Wall. For example, he bought it in 1970 from a store in NYC (I can't remember the name), just a run of the mill strat. I have read excerpts from it, and there is some great stuff in there. PF's equipment tech, Phil Taylor, wrote book about David's Black Strat after being asked by Fender about some of the history of the guitar. But a few of the bass players who did a LOT of stuff played one instrument for most or all of their time. They played tons of different instruments through the years not that there is anything wrong with that. People like the Beatles, the Stones, Zeppelin, the Who, etc.