my 04/HO/auto/ 4/2 has this growl at highway speeds starting from 72 miles per hour, 75 seems pretty rough. If this is normal, I can live with it. petey :-

 

I wouldn't think that any growling is normal. Did you discuss this with the dealer? Maybe you can take the service manager for a ride so he or she can hear it. I definately would not "live with it" on my truck let alone on an '04. Don't let them tell you that it is "normal". Any growling is indicative of other problems.
Tom

 

I have heard and read on these pages of a rearend growl. DO a search at the top of this Web site for related topics.

 

My experience is that growling from the differentials is common with the American Axles used by DC in the 03 and 04 trucks. I finally reset the heel and toe and pinion preload on mine, myself, to get the noise stopped. My personal opinion is that they set everything too loose to try to reduce friction for better fuel mileage. Running loose makes for shorter gear life, but what do they care!

 

growling maybe incorrect. I do know that at 70 miles per hour it perfectly smooth, and at 75 miles per hour the whole truck feels like it has a different personality like the engine is straining. do you agree