|Manufacturer||Arc-Royal MechWorks, Defiance Industries (Kwangjong-ni annex)|
|Chassis||Alshain Type 69-40S|
|Engine||Pitban 320 XL|
|Communications System||Nashan Comm-i U-284|
|Targeting Tracking System||Nashan Trac V-102 w/Active Probe|
|Heat Sinks||10 Double heat sinks|
|Speed||129 km/h (172 km/h with MASC)|
|BV (2.0)|| 1,000|
Luthien Armor Works was working on an upgrade of the Mongoose for ComStar to be a faster and tougher scout 'Mech when the chaos on Luthien during the early years of the Jihad forced them to look elsewhere. ComStar financed a refit of a lost Rim Worlds Republic factory on Kwangjong-ni. New versions of the Zeus and Banshee were walking off the line for battlefield testing when Word of Blake conquered Hesperus II. Anxious to stay solvent, Comstar C-bills paid for the upgrade to the Kwangjong-ni facility. In exchange, Defiance sold them sixty-six percent of its production for its first two years. 
LAW had done most of the work on the chassis, so Defiance turned to Nashan Diversified to outfit the electronics. The result is the Mongoose II, an effective hunter-killer that is able to find hidden enemies and provide long range fire support. An impressive suite of electronics, the 'Mech carries a Beagle Active Probe, Guardian ECM Suite, C3i Computer, and MASC that enables it move up to 172 km/h in bursts. A respectable seven tons of armor protects the Mongoose II.
The only ranged weapon on the Mongoose II is its Diverse Optics Sunbeam ER Large Laser. The ammo-independent weapon is just as potent at long range as at pointblank. With its quick speed, the Mongoose II can also close in to use its fists for quick hits, making this BattleMech an effective brawler.
- MON-267 - This variant is built using a C3 Slave Unit so that it can integrate with the C3 systems in use by the Lyran Alliance. Six and a half tons of Stealth Armor use the ECM Suite to make the 267 a difficult target at range, taking advantage of the long range weapon. A Targeting Computer makes the laser even more accurate. BV (2.0)= 1,237
- MON-268 - A command unit that was still undergoing tests in 3075, the 268 trades out the ECM and C3i for a C3 Master Computer. Ferro-Fibrous armor provides increased protection. In order to make room, the ER Large had to be removed, so it is replaced with three Ramtech ER Medium Lasers guided by a Targeting Computer. BV (2.0)= 1,215
- Mongoose - Though with far more focus on electronic warfare, the Mongoose II was designed as a battlefield replacement for the Mongoose scout BattleMech.
- Beowulf - Also a battlefield replacement for the Mongoose scout BattleMech, the Beowulf BattleMech differs from the Mongoose II in that it focuses on offensive capabilities rather than electronic warfare.
- ↑ MUL online date for Mongoose II
- ↑ Technical Readout: 3075, p. 73
- ↑ Record Sheets: 3075 Unabridged, p. 46
- ↑ Record Sheets: 3075 Unabridged - The Cutting Edge, p. 135
- ↑ 5.05.15.2Technical Readout: 3075, p. 72
- ↑ 6.06.1Technical Readout: 3075, pp. 72-73
- ↑ Record Sheets: 3075 Unabridged, p. 47
- ↑ Record Sheets: 3075 Unabridged - The Cutting Edge, p. 136
- ↑ Record Sheets: 3075 Unabridged, p. 48
- ↑ Record Sheets: 3075 Unabridged - The Cutting Edge, p. 137
- ↑ Technical Readout: 3075, p. 72
- ↑ Technical Readout: 3060, p. 88