Trying to change a 3 way dimmer switch to a 3 way switch
Traveler wires are two wires. But the wires are interchangeable, and there is no need to distinguish one traveler from the other.

Working in conduit, I typically wire travelers as two wires of the same color.  When you're in a 3-way circuit and you see two yellow wires for instance going to the exact same place, those will be the travelers.  

In your case the travelers are probably the two same-color wires on the switch. 

When houses are wired in multiconductor cables, you are stuck with the default colors that those cables are manufactured with - black white red.  As such, you can't go by color code (unless you mark the wire with tape, paint or shrinkwrap).  However, an important hint is that the travelers will both run in the same cable, and that will be true at both ends of the wire.  

Since your wiring is done with multiconductor cable, and none of your wires are white, and there must be two travelers: they must be red and black, and the black will be the one running in the same cable as the red.