With towing that heavy of a trailer and the milage on your truck, changing the diff fluid is a good precaution.

However, as noted, I do not agree with the price.

Also, I would personally not gasket goop the cover back on. I would splurge the $10 for a proper gasket but I am a little **** like that. I think you can even purchase a reusable gasket for a little more.

Finally, if you choose to change the fluid I would most certainly go with a full synthetic fluid. With the towing you do it will handle the heat and pressure better.

Food for thought.

 

Is the front just the same as the rear? Except maybe a little more tricky to get to?

I probably wouldn't for a while since it gets minimal even in winter.

 

The gaskets are prone to leak. That's why automakers use silicone to seal the covers from the factory. It's best to reseal them in the same way when doing maintenance.

And, the factory fill is synthetic fluid, so synthetic obviously should be reused. That's also what the owners manual calls for. You can find full synthetic at places like Walmart for much less $$$. The dealers and parts stores try to get $20/quart for it which is just stupid.

 

I always make sure I can take the fill plug out before I drain the fluid. It's a LONG walk to the closest auto parts store...