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?

 

On the passenger side of the rear end housing, toward the top, there is a plug. You use a 3/8" drive ratchet (no socket, just the ratchet) to remove the plug, and pour it in there. Once it oozes back out, it's full.

I can't picture where you put it in at.

 

I put it in about 2 inches above that.

 

if i had to guess you put it in the breather hole. No big deal it will make its way down to the center section.