I have always thought it was skull (rhymes with dull) and been pretty outspoken about how wrong soul is. BUT, look at the lyrics in my cassette copy of BUSA:
It's also "soul" in the "Songs" book, written by Bruce himself.
But in the Live 75-85 lyrics, soul has been changed to skull and it's very clearly skull in the recording:
So...what is going on here?!