500 miles under 50 mph

I did some research and learned a lot about gearsets in the differential, and how they harden during the break in period through repeated heating and cooling, which causes metallurgical changes to the castings. The concern is that early on they heat up from the friction as the gears mesh and surfaces harden. If the oil overheats the process is corrupted and can compromise the strength of the parts. The speed shops all recommend changing the rear end oil after the break in. As someone who wants a truck to last, I will be following the experts recommendation. I was just a little taken aback by the information. Learn something new everyday.

So the plan is to take it out last twice a day for 15-20 mile drives of varying speed, without prolonged high speeds. Just means taking a long way around to work and home, which should do the trick until the mileage is hit,