When Eric had the diff set up properly, he sealed the rearend and filled both front and rear axles with synthetic 90 weight. At 500 miles we changed the lube and hitched up the trailer for an 1,800-mile trip to Colorado and back. We've experienced no problems. The lower gearing of the 4.30s are very welcome when pulling the trailer. Jane once again has the power of a stock truck when pulling a load.