During the first attempt to use PML's cast-aluminum extra-capacity diff cover, we ran into one problem that is easy to see here: the PML cover is obviously much deeper and hangs farther off the back of the rearend and hits the Panhard bar.... | 
...In a truck with parallel leaf springs and no Panhard bar, this wouldn't be an issue, but on a lowered truck with trailing arms like our '72, it's a major problem. | 
We took our dilemma to the forward thinkers at CPP, and through a bit of in-house R&D they came up with a solution. From the top to the bottom: the stock piece; the CPP adjustable Trac Bar; and their adaptation of their own 36-inch Deluxe Trac Bar that mounts in the same location on the frame as the stock one, but uses a bracket that goes on the passenger-side trailing arm. CPP's Deluxe Trac Bar is ideal for trucks that have been lowered 4 inches or more in the rear, because it lessens the rearend's side to side movement when the suspension travels compared to the stock Panhard bar, plus they bent this one to clear the PML cover so we can kill two birds with one stone. |
With the old diff cover off and the gasket surface cleaned up, use a good-quality RTV gasket sealant and apply a bead to the cover that passes on the inside of the bolt holes like so. | 
After installing a new gasket and the new bolts provided by PML, tighten and torque them down in a criss-cross pattern to 15 ft-lb. | 
Next, the CPP Deluxe Trac Bar bracket goes on the passenger-side trailing arm. The lower shock mount needs to be removed, and the U-bolt needs to be raised up enough to slip the top of the Deluxe Trac Bar bracket between the rearend and the trailing arm. |
The Deluxe Trac Bar kit includes a spacer for the driver's side to raise the left side of the rearend up the thickness of the Trac Bar bracket on the right, and is installed the same way. | 
More than likely, if your truck has its original rearend in it, your U-bolts will look like the stock ones on the right that were more than a struggle to remove. Not only can the nuts be difficult to remove, but once you do get them off, about 4 inches of the U-bolts pass through the trailing arms, and after all these years of trapping dirt and water, they have nicely rusted to one another. You can see how the originals taper in now where all the rust has been chipped off. Well, CPP has just the cure in both stock and extended replacement U-bolts like the ones on the left. | 
As mentioned before, the Deluxe Trac Bar mounts in the stock bracket on the bottom of the driver-side framerail, while the right side now mounts on the trailing arm. In a stock diff cover situation, the Deluxe Trac Bar would be straight, but CPP put the right bends in this one that clears the PML cover. |