Three 20-Pounder Parrott Rifles in South Berwick, Maine
Three US Navy 20-Pounder Parrott Rifles (or 3.67-Inch Parrott Rifles) are displayed around a monument in South Berwick, Maine. The US Navy variant of this Parrott may be distinguished from the similar Army version by the extended cascable capable of taking a breeching rope. The three rifles are mounted on iron display stands. Two of the three are mounted upside down - as can be seen by the position of the mounting points for the sights. The one mounted correctly shows a US Navy anchor marking on the barrel.
According to the information in The Big Guns, the US Navy Registry Numbers are 188, 189, and 247 - the first two were manufactured in 1862 and the third in 1863.
I have not yet seen a period photo of a 20-Pounder Parrott mounted on a US Navy carriage during the war. The Sloop of War Constellation has a reproduction 20-Pounder Parrott mounted on a traditional four truck naval carriage.