It was still SP then. They pulled standard commute consists of harrimans and gallaries. The SDP45s, GP-40P-2s and some GP9s were transferred to freight duties during that time.

Usually all weekend commute trains were powered by P30CHs, although on rare occasions I saw a GP9 on a weekend commute. Weekday trains were powered by both P30s and GP9s.

The P30CHs were HEP equipped and couldn't provide steam heating. The galleries were steam heated but apparently could still provide some heat by their on-board generator. However, the harrimans were totally dependent on steam to provide heat. So when winter rolled around, the three all-harriman trains were pulled by GP9s instead of a P30CH (129, 131, 133 and 122, 128, 140). All harriman consists were pulled by P30CH's during warmer months. Problem was the all harriman trains were 5-7 cars long and the GP9s couldn't keep schedule with the longer trains. So, SP had to double up GP9s and brought back the two SD9s, and occasionally freight GP9s and SD9s, to do so. The all harriman trains ended up with 2 GP9s and/or SD9s, along usually with one other mixed gallery/harriman train (saw this on 124 often).

I recall riding 124 during this time with back-to-back SD9s (either 4450 or 4451 and a freight SD9) and 1 harriman and 4 galleries (a common consist on several rush hour trains). 129 and 140 had either 6 or 7 harrimans. I do recall early on seeing a single GP9 pulling 7 harrimans on these trains.

While I've seen plenty of photos of Chicago or eastern commuter systems assigning a single GP7/9 or something like an RS3 with up to 8-9 cars, SP historically usually only used the single GP9s on the shorter off-peak trains.

The P30CHs were sluggish on acceleration but had a top speed that was often pushed. I was with someone who clocked one at 82 mph between mileposts on a short stint between Mountain View and Sunnyvale. So they were often overall faster than GP9s on off-peak trains because once they got going, they could fly.