From Lexicanum

The Hellhound is based on the chassis of the Chimera and totes a large flamer known as the Inferno Cannon. It is feared by all enemies because of its ability to cover a wide area with flames and cause horrific losses to units that cluster together. They instill fear in a target unit, forcing the enemy to take various checks to find out if they run or bunker down.

The Hellhound has Promethium tanks at on the rear of the vehicle making it quite volatile, and the members of the tank crews are often pyromaniacs who take pleasure in souping up their Inferno Cannons to increase flame output. These modifications are frowned upon by any Techpriest Enginseers attached to their unit, both because they are unsanctioned by the Adeptus Mechanicus and because it can make the vehicle very dangerous to be around.

Due to the light armour and armament of the Hellhound, it has been consigned to the fast attack slots. A group of three of these tanks can pose a formidable threat to any enemy commander.

There are three known patterns of Hellhound as follows:

• Mars pattern - (pictured). More popular amongst Guards commanders as their profile is largely unchanged from that of a standard Chimera, making it harder for the enemy to single them out. The promethium reservior fills the chimeras cargo space;
• Artemia pattern - The Artemia pattern differs in two key ways, it has a remotely operated turret and the cargo space is replaced with a much larger capacity fuel cell. This fuel cell is by necessity very heavily armoured
• Graia pattern - also replaces the cargo compartment with the fuel cell but retains the standard manual turret and a crew of three.

Summary

Technical Specifications
Vehicle Name:	Hellhound	Main Armament:	Inferno Cannon
Forge World of Origin:	Graia	Secondary Armament:	Heavy Bolter
Known Patterns:	II-XVII	Traverse:	360 degrees
Crew:	Commander, Gunner, Driver	Elevation:	From -8 to +25 degrees
Powerplant:	Vulcanor 16 Twin Coupled Multi-Burn	Main Ammunition:	98 shots
Weight:	35 tonnes	Secondary Ammunition:	400 rounds
Length:	6.9m	Armour	Armour
Width:	5.7m	Turret:	150mm
Height:	4.1m	Superstructure:	150mm
Ground Clearance:	0.45m	Hull:	120mm
Max Speed - on road	70kph	Gun Mantlet	N/A
Max Speed - off road:	55kph	Vehicle Designation:	N/A
Tranport Capacity:	None	Firing Ports:	n/a
Access Points:	n/a

Sources

Imperial Guard Vehicles
Leman Russ Chassis	Leman Russ Battle Tank • Leman Russ Demolisher • Leman Russ Conqueror • Leman Russ Exterminator • Leman Russ Executioner • Leman Russ Vanquisher • Destroyer Tank Hunter • Thunderer • Bombard • Atlas
Chimera Chassis	Chimera • Hellhound • Basilisk • Griffon • Medusa Siege Tank • Salamander Command • Salamander Scout • Hydra Flak Tank • Manticore • Trojan
Other	Sentinel • Cyclops • Siegfried • Centaur
Super Heavy Tanks	Baneblade • Stormblade • Shadowsword • Stormsword • Stormhammer • Gorgon Armoured Assault Transport