I don't think they've been delivering LSD to stations since late 2006/early 2007.

The pump/tank has to be certified for ULSD. Obviously, for a while, the ULSD mixes with the LSD that was in the tank.

It takes a while for the LSD to be used up and the tank certified.

What I've read is that some station owners have chosen not to certify some pumps since LSD gives better mileage than ULSD. So, people who have diesels that can take LSD think they're getting better fuel at the LSD pump.

Most likely, they're getting the same fuel as the ULSD pumps.