I have done this winch replacement twice, on two different vehicles. I can absolutely verify that there are 6 bolts holding base of winch to cross member. I found, after trying many different methods, that if the bolts do not turn with 6-point ratchet easily, then the best option is to cut the old bolts off. Since the old base bracket will not be reused, I cut the bolts with an air hammer with chisel head. They are not hardened bolts, so they cut fairly easily, if chisel is sharp. I got a new set of bolts with washers and nuts to reinstall the replacement winch, instead of trying to match correct threads on base. With bolts and nuts, it is a lot easier to reinstall and tighten them in place. And if you eve have to remove it again, it will be easier the next time.
I can also verify that the chain type winch will bolt up exactly as the cable type does, it is a direct replacement. The only issue I had, which isn't a big deal, was the chain type winch doesn't spool the excess chain in the mechanism like the cable model. It allows the excess chain to hang down through the wheel spokes. I didn't like having the excess chain hanging down (my personal issue), so I use a piece of bailing wire to hold the excess chain up out of the way. As I understand it, Toyota no longer sells/stocks the cable type winch. The chain type supersedes the cable one. If you really 'have' to have the cable style, you will have to try to find a good used one, or someplace with left over old stock. I, IMHO, think the switch to the chain type is a big improvement. The cable model was a poor design, which was prone to failure, especially in the 'rust' belt areas.