In response I wasnt refering soley to the OP's question but the general question of why the chain drive was used for the PTO.
the primary drive for the 6x6 setup was refined in the production runs of the fc101 lt95 and the winch was a side winder so a gear driven PTO was the easiest to install and from memory used a helical cross that fit onto one of the intermediate gears. Although I also remember vaguely a setup that ran a normal gear to drive a bevel pinion.

