Characteristics for an American truck, amhibious, 2.5 ton (DUKW) in March 1961

Dimensions 31 x 8.3 feet. Capacity 298 cubic feet cargo; 25 military or 2.5 tons cargo (may be increased under favorable sea and surf conditions. Speed 6 (water)-50 (land) miles. Range 32 (water)-400 (land) miles. Largest equipment carried 1-0.25 ton truck or 1-10.5cm howitzer  or 12 litter patients,

Source

Army forces in amphibious operations (the Army Landing Force). Department of the Army Field Manual FM 31-12. March 1961.