Differential Service

I know this shop is expensive but they are a 24 hour truck shop, very popular with big RV’s and commercial trucks and do good work. I’ve used them before but know they are very high on service charges. I’m willing to pay high if I get really good service. I had the oil changed and fluids checked when I bought it in March at a grease monkey. They replaced the air filter but said nothing about the diff. The noise was new since our last trip in September. I didn’t ask them to check it out because I was not sure it was a problem. Still getting to know this rig. I read about differential noise and what I experienced seemed to fit. When I get it back I’ll know if the noise was corrected. If it was I don’t care that it cost $1300. I’ll check to see what they actually did. If they replaced the oil and all seals the internet says that’s the going rate. If they just changed the oil should be less. But I think they will have it apart to check the gears for wear. I think by using them I will be able to keep this RV in good shape. That’s worth a lot. I have a warranty plan but I bet this is not covered. Considered a maintenance issue. I’m going to check.