I don't think you're going to find they've written the notation down, nor can I imagine any system that could turn this sort of sound-file into written notation. It's not performed to a strict tempo, and the three parts don't start each chord precisely together. They don't always have the same person singing the melody, either.

But human ear is your most useful asset. If you're really into acappella singing, it shouldn't be too difficult to work out the harmonies for yourself, listening to a recording. Or better still, listen first and then work out broadly similar harmonies that suit your group and the ranges and qualities of your voices.

I'm always astonished at how different a harmony trio sound from any other harmony trio, because of the individual qualities of the voices and the ways they arrange the parts. The Voice Squad always seemed to me to have a style that relied on listening closely and tuning in to the others, a quality that would not have come across the same way if they'd been working from sheet music.

Here's a tip: if you're listening to a recording and trying to pick out which voice does what, use headphones. This enhances the stereo effect and makes it easier to untangle the parts.

I loved the Voice Squad and am sorry they are no more. They applied an English style of singing to mainly Irish songs and it worked wonderfully well.They were a delight to listen to in live performance, too.

Good luck.