The DANA OEM rear end in my GTO was a serviceable and reliable unit that held everything I threw at it for 90,000 miles. In fact, I have broken more on the Ford 9″ than I did on the DANA. The first major modification we made to the differential was adding a Harrop cover to it around 15,000 miles. This cover increased the capacity of the lubricant in the differential and I think contributed to the longer life. The Harrop cover also offered enhanced mounting that did help the wheel hop issues some but eventually I over drove it and just moved my wheel hop issues to another place in the rpm range. We changed the stock 3.46 gears for 3.91s at 22,000 miles. I purchased the Gears from Difftechnics in Austrailia along with a major overhaul kit and the LSD spring ennhancement kit. In my opinion the spring enhancement for the LSD was a hugely successful modification and contributed a lot to the long life of the OEM differential unit, especially the limited slip differential.