Mine makes a horrible grinding noise like yours Cookie Monster. Mine usually only did it in 4th and 5th though. To check it out I put the truck in the garage, rear axle jacked up, blocked, back tires off and had my dad row through the gears while I was underneath. From the best of what I can tell it is coming from the U-Joint on the driveshaft. I plan on making a CV style one to replace it this spring though, so hopefully that will solve the problem. That is another reason for raising the front mounts, becase it gets the driveline angles closer to stock. What do you have for a rear driveshaft?
