It's a sad fact but bubkas is the answer...
I saw him singing solo as 'The Heptones' two years ago; he did a lot of their classic stuff, and some other Studio One classics,with a really tight band, wonderful show. I definitely missed the harmonies but it was great to hear him live.
These following clips feature Lloyd Parkes with his We the People band backing up
Dennis Brown and U-Roy respectively, from the late '70s. He was just as often if note more so more often seen playing Precisions, for what it's worth. He was a member of the Revolutionaries with Sly before Robbie Shakespeare became his musical spar; I love his Channel One recordings from the era, especially on the Big Youth 'Dreadlocks Dread album:
http://www.youtube.com/watch?v=uMAmiK4ES6I http://www.youtube.com/watch?v=OiDlRChgJj8
I have a great Documentary with a clip of The mighty Diamonds playing at a small club in JA with Parkes and the members of the Soul Syndicate playing 'Right Time'; it used to be up on youtube but it seems to have disappeared. Insanely tight band, really exciting performance.