Thread:User talk:CodeCat/h₁reudʰ- or h₁rewdʰ-?/reply (3)

Yes, I'm very sure. They are one and the same phoneme. The same with the other diphthongs ey, el, er, em, en. But you are correct that the form *ud- has a vowel. That's different... when they were converted to vowels they were actually vowels and could be stressed.