Remember that there was Gold Mountain, and after a resurrection it became Gold Mountain Technologies, but with different equipment
Most of the original Gold Mountain models were TR Disc. models, and some were VLF/TR-Disc .models. Of them my favorite was the last of their run which was the Gold Mountain VIP Deluxe. The VIP came with one search coil, and the Deluxe came with a larger 10" coil included. That was how many manufacturers sold detectors back then, using a model name that noted a 2-coil package. I was selling and using the VIP Deluxe about 29-30 years ago so you can imagine what it lacked with what we have now.
You can contact Sven via e-mail at treasurelinx@yahoo.com to get connection info for the old Gold Mountain catalogs. Then match up what your acquaintance has. In the end, however, while it might be an interesting older model, and might even work for some applications, most of those very dated detectors just aren't worth a hoot by comparison with the more recent offerings we have today.
Monte