The first bottle I put into the hold on top of the diff housing. It had a little cap on it that I just took out. There was about a 1/4" hole there. I figured that was the one. Then I noticed oil started coming back out before I even put the first bottle in.

So I took off the fill hole bolt on the front off the diff, and to no surprise, nothing came out. So I put the other bottle and the additive in this hold.

My question is, where did the oil I put into the upper hole go?

 

Check your other post.