I put that pulley with some shaft/insert there but there is a gap between grooved and this one pulley like 1/4 ". I recall there was no gap before. What I think that original idler pulley had bigger bearing inner diameter so it sit further on that shaft eliminating gap. It works now. At least rotating freely without any side "plays".
I went to few junk yards and none of them has it. At least that'* what they said. I honestly don't believe it. None of them has 3800 GM engine? Those Tony Soprano types sitting there and this is just something not worth to move their arses for.
Probably some small town junk yard would be far more helpfull then here in NY.
Edit: Forgot to say I put metal pulley this time from spare tensioner.