100% Traction On Demand – ARB Air Locker

Our ARB Air Locker install involved three components; the locking differential itself, an ARB on-board air compressor kit, and Driveshaft Shop inner axles made for the ARB unit installed into the Driveshaft Shop 9" IRS conversion housing in our project car.

Everyone knows by now that it's not hard to make amazing horsepower with the Gen III HEMI engine. Want 600 horsepower? Take a stock SRT and bolt-on a Magnuson supercharger like we did and, boom! You have 600 horsepower at the flywheel with full C.A.R.B. 50-state smog legal certification. It wasn't so long ago that this was mega-buck exotic supercar kind of power. The golden age of muscle cars is here, right now, just in case you haven't noticed.

Of course, when you add power to a stock vehicle, you tend to find the weak links in the chain between the flywheel/flexplate and the rear tire's contact patch. But even with 600 hp, if you judiciously select the right parts, as we did with our factory 215mm Getrag rear end read about it here:, you can happily enjoy your modern muscle car on the track and the street.

However, a whole lot of late model Mopar fans are no longer satisfied with 600 horsepower. We weren't, so we upgraded the MoparMax Maulin' Magnum to an 800 horsepower Magnuson blown Arrington Performance engine. And that's when we found out that the 800 ponies are an order of magnitude harder on parts than 600 of them are. We broke everything on our car, two or three times actually.

The very first casualty of the "Arrington 800" was the beefed up Getrag rear. As soon as it failed, we knew that repairing it was pointless. There was no way a split case, aluminum housing rear was going to live with the punishment of the power and torque we were now trying to apply through sticky drag racing slicks. Since we were seeing more and more high horsepower late model HEMIs at the track, we sought out the most bullet proof solution we could find to share with our readers. We ended up installing a Driveshaft Shop 9" IRS conversion kit and have never looked back.

While we are thrilled with the DSS kit and haven't suffered any gear or housing failures, we can't say the same for the various limited slip differential (LSD) options we have tried within this great housing. At the drag strip, you need both tires to spin identically during the burnout and then you need engine power to go equally to both the left and right tires at launch. We were never able to achieve that with any of the LSD options we tried.