Many years ago, SWI (SouthWest Industries) had a Trav-A-Dial unit where the reader head was mounted on the desired axis, then the signal was fed through a cable to a DRO that looks very much like a newer Acurite. There wasn't a mechanical dial like a standard Trav-A-Dial.
I haven't seen any around, so they probably went the way of the dinosaurs.
We had a 50" TUDA lathe that I mounted a set on. A heavy piece of square tubing was whittled down to provide protection for the cross-slide or X-axis unit. For the Z-axis it was not as complicated of an installation.
One odd thing about the readout was that it only counted to 36" IIRC, so you'd have to reach up and reset the readout for the Z-axis if the anticipated travel was over that. Rarely needed,
and not a big deal.........unless you forgot.
That was back in the 80's. Kinda wonder if it's still doing the job or if it's been supplanted by newer technology.