Anyone from the bay area? west side of the bay?

ok as many of you know there is caltrain but after operations stop at night the freights start to play. now i have seen it once but i didnt see the number on it but evey weekday theres a un-marked rio grande GP40 or GP40-2 helping with a UP GP40 and i wanna know if anyone else has seen this? cuz ive missed it with the blink of a eye and clumsyness[banghead] but if anyone could get me the number on this loco i would [bow] to them

-the feed