Complex sentence: The M31 consisted of a truck-mounted, unguided, solid-fueled rocket that was transported in three separate parts that were combined in the field, mounted on an M289 launcher, and aimed and fired in about 5 minutes.
Split into simpler sentences: The M31 consisted of a truck-mounted, unguided, solid-fueled rocket transported in 3 separate parts. Before launch they were combined in the field, mounted on an M289 launcher and aimed and fired in about 5 minutes.