Based on the available information, the boat ramp named Old Yellowstone Trail Park County is located at latitude 45.25366592 and longitude -110.87095642 in Montana. According to the Montana Fish, Wildlife & Parks (FWP) website, this boat ramp is a concrete single-lane ramp that provides access to the Yellowstone River.

The boat ramp is approximately 12 feet wide, which is enough to accommodate most small and medium-sized watercraft. However, it may not be suitable for larger boats or those with trailers wider than 12 feet.

The Yellowstone River is a popular destination for recreational boating, fishing, and other water-based activities in Montana. It is the longest undammed river in the lower 48 states and offers a range of opportunities for anglers, paddlers, and boaters.

According to the Montana FWP, the Yellowstone River is open to all types of watercraft, including motorized boats, canoes, kayaks, rafts, and paddleboards. However, there may be restrictions on the size and horsepower of motorized boats, as well as rules regarding fishing and other activities on the river.

It is important to note that boaters should always check the latest regulations and restrictions before launching their craft at Old Yellowstone Trail Park County or any other boat ramp in Montana. This will help ensure a safe and enjoyable experience on the water.