Whatever you do, make sure that whoever is working on that IRS system knows what they are doing. Just had a situation with mine before it went out on the 5yr 50000 mile warranty. I had a slight whine, I took it to the local dealership in Milledgeville,Ga. to have it repaired. I had already looked at the shop manual, and it's not the same as a regular 8.8 setup. All of the certified Ford mechanics left for better dealerships and one was still there. I requested him to look into it and asked if he was familiar with the IRS. Any how, he was pushed to another job and they put a jack leg on it. I went to check on the progress and found the truck on the rack with the brake calipers hanging by the lines....the axles are pulled out and the CV joint boots are resting on the frame...they were torn. The carrier is on the bench and I was told they "broke a shim"??? I get the truck back, the whine is still there, grease is slung all over the place from the split boot. I bring it back, they put a NAPA boot on it, I get home and the right boot is busted. Any rate, I got the truck to my selling dealership close to the Alabama line and they take the job under warranty(good friend of mine, but he's 3 hrs away) and Ford back billed the dealership here. They had to replace the carrier( it was cut with a ziz wheel cutting out the bearing),ring and pinion, bearings all boots etc. The tech at Pioneer Ford advised the rear ends on these trucks were a little noisy and it is exaserbated by the aluminum housing. They must set the pinion depth differently than specified to eliminate the noise. All is good now...just be forwarned.
