RFD, many thanks. Then some Chile questions

Thank you to those posting a heads up about the San Juan program on RFD, great stuff!
Naturally, it brought some questions to mind about the Chile Line.
K-28s appeared to be the largest locomotives used on the Santa Fe line. Did K-27s ever get down there, or did the lack of steam heat and signal lines prohibit that?
Did anything bigger than a K-28 ever have occasion to travel any distance south past Antonito, or was weight the consideration?
In the last 10 years of operation, did pure freights ever run to Santa Fe, or was it always a mixed train?
As always, answers to these, and any other questions I haven't asked yet are appreciated...
sda