Standard nomenclature lists. F-294. Mount, telescope. M55 (T85) (for 76 mm gun motor carriage. T70), mount, telescope. M56 (T83) (for 105 mm. howitzer M4), mount, telescope. M57 (T82) (for 76 mm gun M1A1 and combination gun mount), list of all parts; Dec. 2, 1943.