There were some 727 combis made. Reeve Aleutian and Air Mike (Continental Micronesia) operated them I think.
And didn't Eastern and Braniff operate 727 QC's with interiors that could carry seats or pallets?
UPS operated five 727-100s with Rolls engines that had swappable cargo and pax interiors. The interiors were supposed to be usable on any of the five aircraft but, well, the holes didn't exactly line up.
