Nobody has yet mentioned Andy Fraser?I really love his playing with Free: wonderfully understated yet funky and the tone he got from his Gibson EB-3 through the Marshall stacks is sooo gorgeous. He's without a doubt one of my main bass influences. Here's a youtube clip from the 1970 Isle Of Wight festival of them playing my all-time favourite Free tune, "Be My Friend".
http://www.youtube.com/watch?v=leGAYNe2UzU
Dang, you beat me to it!
(Racks brains)
Dan Lilker played a medium scale Jackson with SOD...