I have a 1998 chevy silverado with 411 gears and 295/30r/26 tires but my problem is that when I'm on the highway it howling really bad should I have went with 3.73 or what the best gears for me with my tire size or do I need a programmer to fix the problem I need help asap

 

are you sure it's the rear end making a noise ? it might be low on grease, a bad axle bearing, the pinion gear, the tires can make a noise and also the kind of road will too !

 

I'm sure it didn't start till after a month. when I got my gears put in it roaring like it needs to go into another gear

 

So the differential was recently rebuilt? The gear ratio will have nothing to do with making noise but bad bearings or setup will. Try to verify the noise is front or rear it could be wheel bearings also.

 

I'm a little cunfused about what's howling. Sounds like maybe you're talking about the engine howling. If you went to 411 without increasing your overall tire/wheel diameter much, you will experience higher rpm's at highway speeds.

 

I'm sure it coming from the back it like a loud revving sound as I'm going down the highway

 

I increase my rims size to 26 inch wheels

 

what kind of tires do you have? was the noise there before? Otherwise its time to get it on jackstands or a lift and stethoscope the bearings

 

Depending what type of tires you have, they will cause a howl. If you just had those gears installed, if the mesh is misaligned just a little to far off, the new gears will howl. And cause premature wear.