Thanks, Hans.
Interestingly, when shooting some pics to send you of my wife's D35, the oblique angle of the close-up flash (boy its hard getting good shots w/o reflections!) revealed a trace of finish marking where the old 3 in-line machines had been attached on one side of the head. You still can't see it on the other side. The flash also revealed what appear to evidence of the marks being buffed out. Looks like the Grovers were an upgrade at some point... from the faintness of the markings in the varnish, I would think it was fairly early in the life of the instrument. I bought the guitar second-hand for my wife in '86... so I know it was before then. If you are interested, I can still send the pics. But, I think I have satisfied my curiousity... If I ever see a set of the in-line machines on eBay, I might pick them up to "restore" the instrument to its original specs... but I am more a player than collector, so it isn't a priority.
Thanks again, Dave