Product review (4 stars): yep, it's a tensioner pulley and bracket.
yep, it's a tensioner pulley and bracket.  Fit well, installed easily, machined well enough I suppose.  I don't trust the plastic triangle clip to hold , and it was missing on my existing one making me suspect that was the failure mode.  It's nice to be able to fix my own dryer, particularly given how simple these machines really are and how much the local appliance repair services want.