FYI, Dana has changed the offset of the Pinion bearings on newly manufactured Dana 60 center sections by 0.100" making all previous spools and diffs not fit. We had to mill down our Mark Williams spool to get the ring gear offset correct. We tried both offset spools (the one for 3.90 and up, the one for 4.11 and down). Hard to believe they would do this and not give it a new number (Dana 62?) but Mark at ProGear in San Diego who builds our race rear ends called Dana and they confirmed it. Our new Dana 60 center section was a newly manufactured one delivered to Summers Bros who installed the chromoly axle tubes. Pro Gear in San Diego has also just now seen this on a new Ford E350 when they tried to upgrade the diff. I don't think Reider Racing or any of the other resellers know this yet so beware.