The one thing i do "know" is (because i saw it on a what guitars on what zepp songs write up many years ago) he did NOT use his paul or tele on that track, it was his Danelectro!! I havnt been able to nail the tone on this track completely yet, but, i owned a DAN about 30 years back, long before i saw that write up and as soon as i saw that i flashed right back to my Dan and there it was, the missing piece!! I borrowed one from my wifes nephew one day, plugged it into a line 6 pod that had a vox ac30 program in it and right off, that was the ticket. There was some tiny bit still missing but if i played that tune in a band today, i would get one of the old red kidney bean gen2 pod's, grab a danelectro guitar and be 98.5 dead on the money with that HOTH tone. Then, not long ago i was in a gc store and a college kid was trying to sell his DAN to the store. I saw the sales guy take him over to the amp section and the gc guy plugged it into a used 50wt plexi reissue and started playing and i butted in and asked him if he knew any zep tunes. He said not anything he would try to play so i asked the college boy and he said its his fav band and knew a bunch of their stuff and its why he had the DAN. So i asked if he knew HOTH and he launched into it and even with a 50wt marshall 90% of the tone was spot on. The DAN is the biggest part of that songs magic. So......, my conclusion........, Danelectro guitar. Vox AC30. (or clone) Run it through the phase reverse trick mentioned by an earlier poster on a analog recording desk or plug-in that has the phase button/switch on it. Small bit of delay. Very light footprint of reverb and i believe that is that. Hoses Of The Holy in the bag!!