Warrior Ancient and Medieval Rules

Greetings,

Under the notes for the Ugarit List #15 it states that "The Ugaritic
option represents one of the more powerful confederations that also
used three-horse heavy chariots with an added armed crewman".

I cannot find anywhere in the list where it gives you the option to
add a third horse. The list says " Extra to upgrade Ugaritic Maryannu
chariots to two horse HCh with 2nd armed crewman with JLS or B @6..any.

Is there a mistake here?

KT