differential service?

So, I have an '05 F-150 and I took it to get oil changed and tires rotated today. Every time I've gone for an oil change, they've advised that I get my rear differential serviced. But the first time I went they said not to worry about it until it hit 45,000 miles (I'm at 32k right now and was at 10k at that point). I haven't pulled a trailer with it in the year and a half that I've had it, and am unlikely to do so in the immediate future. Does anyone know when I should actually get that taken care of?

If it does not make any noise,leave it alone and the dealer is trying to do something unneeded.Only thing to do is change the gear lube once in a while and if it has a posi,put in posi traction additive you can get at most parts store.Put the posi traction additive in first before the gear lube if it has posi traction.

im sure the info you need is in your owners manual or the dealer will provide you with a maintenance schedule

05 prolly has synthetic in it. Good for the life of the truck usually, unless something happens like heavy usage, water getting in, or a leak. Those places are always trying to sell people things they don't need. They seem to use a set maintenance for all vehicles. It use to be that all vehicles were pretty much the same but not these days.

Looking at the 05 F-150 schedule normal driving, I see nothing about rear diff service. Towing it shows every 60k. Check it out, put in your truck's info and your driving conditions.
http://www.genuineservice.com/genuineservice/en/default?page=Home