From Halopedia, the Halo wiki
The Foundry's garage and its kit assembly line allows the requisition of a Banished Ghost. Interestingly, in a departure from the Covenant era Ghost designs, the Banished Ghost appears to have plasma reactors on both sides of the chassis, instead of just the right side. 
In March 2559, the Banished used their own modified version of the Ghost with energy shielding during operations against the crew of the UNSC Spirit of Fire on Installation 00. In 2560, the Banished fielded Riuctda Workshop Ghosts on Installation 07.
Halo Wars 2
In Halo Wars 2 the Ghost is a unit exclusive to Shipmaster Let 'Volir and Ripa 'Moramee. Like its Halo Wars counterpart, it can be upgraded to have energy shielding and can be used to gather resources. Being cheap scout units, Ghosts only do okay against infantry and vehicles and perform poorly against aircraft and structures. It costs 30 resources in Blitz.
List of appearances