My son and I drove up to Toluca on the old Sante Fe route to see the joint train last night. Like the above post says they were doing some bridge work on the Mendota line.
Unfortunately, it had lost about 90 minutes by the time it went through at 6:00pm, so we had to see it in the dark. They were bascially running #3 in the front, with #5 attached to the back setup in reverse (I was wondering if they had flipped the coach chairs or were making people ride backwards). It would have been fun to see how they split the operation in Galesburg.
They did the same thing last year when the Mendota line was clogged up with snowdrifts, although I don't ever remember them running the trains as one consist. I assume they did this at BNSF's request as the old Sante Fe Transcon line is very busy with high priority intermodal traffic (although in the hour we waited, we only saw one westbound intermodal and one eastbound oil train).