Differential oil blowing out

John Trickler said

I did not move the vent, that's where it was when I put the rear end in. I put the RMS suspension in. Is a mystery.

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I’m going to catch hell for it, but I’m going to say a cheap (relatively) fix is to change the gear oil.

I don’t know what you are using, but cheap gear oils foam like jack the bear.

It may be just a simple oil change. It may not entirely fix it, but it may help.