ugly river

I think he has more busted FDs here than straights. Probably river could be check/call.

I don't think that he is calling the flop with T9 or J9 very often and he doesn't have K9 very often there. 99 is possible, but he is sometimes folding the turn with it. There is a perfect spot on the river to bluff + he is a reg and might know that. I think he has busted flushdraws often enough to check him out. Tought spot, though.

This is never really a bluff at nl5. big question is would he raise a worse hand? Might call here against some.

As a basic move check call river.

I think that the majority of your range should be checking the river. I'm not sure on your river bet unless you think he's going to call with random 2p/sets. As others have said, it's the perfect spot for him to turn a hand into a bluff and I think you should probably just check/decide (if he bets).

If we bet here, we should fold to a raise with 4-to-straight on the board.
98 is the very possible...