[revoluteme]

On the turn you are are a 58-41 dog to a random hand, which it seems like he could almost have, and by the river you are 2-1 so the check is almost certainly best given his ability to call on the river with mediocre holdings, although this is considerably different than the hand he did make that call in.
overall it seems to be an ok play to get a showdown for the least possibly while still giving you a chance to win without one, but expect to lose more often than not after the call on the turn.
now, what would you have done on an 8 (not diamond we'll say) river?