ARB has released this ultra heavy (duty) diff cover. It's made of cast iron! We offer them in black or red. These are really a super nice cover and very heavy duty. I really dont think you could break this even if you tried. These covers offer nice fill holes and even a dipstick to check the oil level!! The cover also has magnets in the plugs to trap any ferrous debris. Another nice feature is that the hose/wire bracket is included with these covers...fancy. The press release, what all the other vendors post, says "computer designed, blah blah, for extra strength" On this i call busllshit. These are very nice and super tough, but there is no way these covers will improve the case/bearing cap strength (ask yourself how many axle failures there have been with the stock stamped cover...none). The cover is super strong, but everything around it is weaker than the case...adding this cover will not strengthen the other weak links. It is important that you, the customer, are not misled. We often get asked to compare this cover to our cover and the BTF to mag-hytec these, so, here goes
-weight...PRG is lightest, ARB heaviest, BTF and MHT in the middle
-Leak-proof...PRG, MHT, and ARB both have machined mating surfaces...no leaks welded cover, well..
-Capacity.....MHT is most, PRG second, BTF then ARB...this really is trivial as the extra capacity will get you and extra 30 sec before failure if there is ever an issue..but the ARB is less than stock.
-Cooling....Stock finned titan is best, then MHT, PRG, BTF, then ARB
-smash protection...ARB, PRG, BTF, MHT
-dragging over rocks protection....PRG and ARB tie, BTF and MHT can both bend and leak
-Price...BTF $130-ish, PRG $149, ARB $199, MHT $220-ish
These covers drop ship from ARB. Black covers are usually in stock. Red covers are sometimes in stock. We'll let you know the status post ordering.
 
Here is the same techno-jargon posted on everyone else's site

When off road, it is inevitable that obstacles and off road hazards will be encountered that could potentially inflict expensive damage to your differential. to prevent this, ARB manufactures the differential cover. Using high tensile nodular iron, it has been engineered to protect the differential and ring and pinion set from any off road hazards.
Features:
Computer optimized cross brace design increases the structural rigidity of the whole axle
Additional housing strength helps keep the ring & pinion gears meshing on the flat faces of the teeth, greatly increasing ring & pinion life and overall maximum load strength
Top quality, high power neodymium magnets are used in both the drain plug and the dipstick to collect metallic wear particles as the vehicle moves
Magnet location in the end of the dipstick allows the oil to be checked for tell-tale signs of internal damage
Prolonged carrier bearing life due to extra support to the bearing alignment
Approach/departure angle optimized by angled exterior surfaces
Unique dipstick/filler cap design allows differential oil level to be adjusted for customized high driveline angles
PS, this cover fits the dana 226 axle in all Titans, offroad/pro4x Xterras, Nismo/pro4x Frontiers, and all 6pd manual versions of the Frontier/Xterra. When ordering, it may say frontier, even if you ordered from the titan section...dont fret, it's all the same.