Not gold, not chrome-plated. Brass. I've seem them on DBs of course, & recall seeing lots of brass parts(bridges, nuts)on 70s basses, particularly Alembics. I'm slowly amassing parts for a P-clone rebuild/mod project, and want all brass hardware. I just snagged an old Mighty Mite bridge & brass nuts are pretty common, but not so much on tuners. I'll go gold if I have to, but thought I'd tap the collective mind here first.
Brass would be too soft for the stresses under which tuners work. Bronze would work, but not brass. I don't doubt that someone has tried it, but the lack of availability tells the story.
Don't mean to bump, but Schaller makes bass tuners with brass posts. Brass, depending on the zinc content, does not have to be all that soft. http://schallertuners.com/category/schaller-bass-tuners/ It CAN be heavy, though.
Most of the older style open gear tuners are made from brass, which is then nickel or chrome plated. If you want them to look like bare brass, you can take the parts to any plating company, and they can strip them for you. But, then what are you going to do? Bare brass will tarnish and corrode quite quickly unless you either coat it with some kind of clear poly or lacquer or keep it constantly polished and waxed. Either one of those things is problematic on small machine parts like a tuner. Are you specifically looking for that old brownish tarnished brass look? That's what bare brass will look like very quickly.
No need to send them out to be stripped, just get some nickel plated brass units and some brass black and strip away. Here's a link to a thread where I described how I stripped some nickel plated brass bridge saddles. http://www.talkbass.com/forum/f18/grooved-brass-bass-saddles;-can-i-get-hold-them-990406/