Ijust put a 4.10inmy king ranch, and at around 50 mph when I back off a lil bit, there is a whining sound. I was told that this is normal. I used to have a mustang 97 gt, and in that I had a 3.73, I didn't hear a whining in that. Is it just b/c it is a 4.10 gear and that it is a truck? Am i the only one?

 

I have the whinning 4.10's also. Two mechanics have said it is set up right, that it must be the gears. I bought from Randys Ring and Pinion and they will not replace. I wish I had bought from Drivetrainwarehouse. They advertise no hassle guarentee. I think the new gears should be as quiet as OEM

 

A whine over a small speed range can be several things. With new gears it's generally crappy gears or poor backlash setting upon installation. One that develops over time can be crappy gears or out of whack backlash due to wear, contaminants, or improper lubrication. High quality gears+clean,proper installation=no noise.