Rocket Artillery Systems
(Source: TM 9-500, Data Sheets for Ordnance Type Materiel, September 1962)
Launcher, 762-mm Rocket, Truck-Mounted, M386, W/E
See below for general description (TM 9-500)

LAUNCHER, ROCKET: 762-mm, truck-mounted. M386, w/e, is a mobile, heavy field artillery type launcher which provides a base for launching surface-to-surface, large caliber, free-flight, fin-stabilized rockets. It is composed of the 762-mm rocket launcher (ORD No. 8417300) and the 6-ton 6 x 6, M139 (modified) chassis. The launcher M386 consists of the chassis which is equipped with a gasoline generator set M26, launching beam assembly, elevating mechanism assembly, traversing mechanism group, equilibrator assemblies, and the electrical system. Three screw-type jacks are need to provide stability when elevating or firing the launcher. Elevation of the launcher is either done manually or by power. Traversing is accomplished by a rack and pinion which is operated manually.