I think something is missing from your post...

 

Yes technical difficulties

 

Yes technical difficulties

 

The rear diff didn’t drain? Oh boy. I hope you got it on camera… I’d want a replacement diff put in by the dealership.

 

No. I meant it didnt run out the fill hole. Fluid is yellow. I cant post pics for some reason

 

Most gear oil will look golden when new and clean, so if your fluid looked golden and not dark/grey then you're fine, gear oil sounds like it was in great shape. Gear oil not coming out of the fill hole prior to draining is no big deal as long as it's close, you should be able to stick your pinky finger in the fill hole and touch fluid. Too late now to know if it were within fill spec or underfilled, but since the gear oil looked clean I wouldn't have any worries.

 

Has 100 miles on it. Was sitting overnight. No water crossings. I'm wondering if the factory fluid could be contaminated?

 

Sure looks like it could be, though with only 100 miles on the truck what made you decide to drain the factory fluids? The diffs aren't even broken in yet.

 

Kind of looks like factory dye added.

 

That color makes me thing of the "gear marking compound" that is used to check the Ring Gear:

 

It sure does! Little crazy with it.

 

While a little odd, I don't think this is cause for concern. My first thought was the same as @gherbert had, and I think that's the most likely one.

 

Thanks. It really didn’t look like water. I wonder if that color goes away after so many miles. I’m gonna send it. I’ll see what it looks like in 10k more miles. Only has 100 miles on it.

 

Why are you doing that so soon?

 

I was just checking the level.

 

Seems to me the factory fills to a spec. volume , (1.25 quarts ?) not to the fill hole. That is why all our diffs seem low before we change fluid. I question if this add heat to the diff gear set. When I got my free first oil change I asked them to check the diff and he said" there is no dip stick, so we don't check it". Just my 2 cents..
Luck

 

If ya can feel the fluid level with your pinky in fill hole your fine. But that color is odd.