I'm a little curious about this as well, my seat bases are loose and rattle quite a bit, definitely has some wear and tear on them (although you wouldn't notice it, the seat cushions/covers are in great shape). I'm just a bit annoyed with the rattling and I'm not sure that they are completely safe, being loose like that.
I've been somewhat looking for charcoal leather heated tahoe seats, but that would be a serious make-work project with some wiring to figure out and fabrication work to bolt them in. It would be worth all the effort though.