Information from Grumman Aircraft since 1929 by Rene J Francillon.
GG-1: The first civil registered aircraft built by Grumman. Assembled from major components remaining after production of FF-ls and SF-ls had ended, the GG-l was an unarmed company-owned demonstrator which was initially powered by a 450-hp Pratt & Whitney Wasp radial and fitted with modified canopy. Registered X12V, the GG-1 first flew on 28 September, 1934, and was retained by Grumman until 1936. It was then re-engined with an 890-hp Wright R-1820-F52 radial and, after its US registration was changed to NRl2V, it was sold in November 1936 to Canadian Car & Foundry to be used in promoting the ‘Canadian Grumman Fighter,’ an export version which was to be assembled in Canada. In December, the aircraft was flown back to the United States, by Howard Frederick Klein, where it was demonstrated at Floyd Bennett Field, not far from Grumman’s Bethpage plant, to aircraft purchasing agents of the Spanish Republican Government. In 1937, Canadian Car & Foundry sent the aircraft on a demonstration tour of Central America, during which it was lost at sea on 29 September while flying off San Juan del Norte on the Nicaraguan-Costa Rican border.