All of this region was cleared and populated in the early 1900's. It had a large population (over a thousand people lived in this area), but it was short lived. Due to the challenging weather conditions, steep terrain, the lengthy travel to and from the nearest towns (Foster, Toora, and Boolarra), this area was abandoned by the 1950's. In the 60's onwards, a lot of this area was then planted out with Mountain Ash trees by the prisoners of the nearby Morwell River Prison Farm. Boolarong used to have a school, hall, numerous houses and farms, and many other facilities. Their used to be regular events and sporting days held with regular competitions between residents of Boolarong and Gunyah.
Beware of traffic along the road (especially log trucks and gravel trucks). Be warned, there are numerous leaches that crawl around this area. I should also add, Grand Ridge Rd + Boolarra Foster Rd is drivable in a 2WD vehicle, but you may be more comfortable in an AWD or 4WD. Some sections can be muddy and potholed, but is regularly driven by tourists on the weekends.
You're looking for a bison cache. Located at the Gunyah Junction School site. During its operation, there was a road up the ridgeline to where the Gunyah Rifle Range was located on top of the hill behind the school. Nowadays it's very overgrown, and there's a few remnants of the rifle range (bricks, bullet casings, nails, etc.) but very little remains.