A brace of Southern Pacific EMD’s pass through Tunnel 2 on the Tehachapi grade. The slide labelling indicates that these are helpers, so they are going away from the lens.
The next two units are Kodachrome 9207 a SD45T-2 and SD45M 7429.
The track in the foreground was Santa Fe's.
Westbound California Zephyr gets some help from Southern Pacific