OK, I reviewed JRRT’s earliest notes on the trip thru Moria in “The Return of the Shadow” and subsequent notes in “The Treason of Isengard” and in all scenarios Gandalf stated he thought there was at least one troll leading the attack party. In the 1st draft of the attack in the Chamber of Mazarbul, the passage reads “An enormous arm and shouder with dark green scaly skin (or clad in some horrible mesh) thrust through the widening gap. Then a great three-toed foot was thrust in also.”
Boromir’s sword gets notched as before, and Frodo wounds the foot, and his sword drips something that smokes when it hits the stone. Battle continues, mentioning only orcs, of which, 13 are slain and the rest flee. Then, (quoting from the book) “‘Now is the time, if ever’ said [Trotter >] Gandalf, ‘before that Troll-Chief or more of them return. Let us go!’” But then Frodo gets skewered by an “orc-chief”.
It appears that this sentence, said by Trotter in the 1st case, changed to Gandalf, implies that a troll was there. And on page 201 of “Treason” CJRT comments on the evolution of the story: “…the troll becomes ‘a great cave-troll’ as in FR, and its three-toed foot was changed in the manuscript to a toeless foot.”
So CJRT himself believes that the foot that Frodo stabbed belonged to a cave troll. I am so not going to try to argue that he was mistaken.
Otherwise, two trolls appear later as described in FR, in some drafts carrying orcs over the flames, in others throwing slabs over the flames.
Also, interestingly, Gandalf at first faced a Black Rider on the Bridge at Khazad Dum. But this was crossed out and changed to ‘Balrog’ in the earliest draft (Return of the Shadow, pg. 462.
So having reviewed the author’s initial notes on the subject, along with commentary by his son, I now officially recant and say that Yes, the fellowship faced a cave troll in Moria.