Black Dog - I actually have not looked too closely at that one, but I will. I read in Thunder of Drums that Jones said Bohnam had trouble with that tune. What was trouble for Bonham? The band had to play it twice before he got it?
the trouble is that plant sings each stanza in free time blues style and then the band has to come in, all together and all at the same speed. if you listen very carefully you will notice the rest between plan'ts last word and the entry grows gradually shorter...
Hey, hey, mama, said the way you move
Gonna make you sweat, gonna make you groove
.... (longest gap and then in come the drums and guitars)
Ah, ah, child, way you shake that thing
Gonna make you burn, gonna make you sting...
Hey, hey, baby, when you walk that way
Watch your honey drip, can't keep away
.... (almost no gap)
and buried in the last words each time you will hear a stick click.