He's unknown regular.

Preflop:
Its my last suited 9x in my calling range, im mostly mixing 3b/calling with these.

Flop:
BDFD and gutter, versus sizing i think i can call it being IP. Without BDFD prooopably foldin.

Turn:
Ouch. Good card for me, but also solid sizing from his part. He's giving me 29% potodds and i have a bit less equity if we consider my all outs are clear. Having BDFD and not-obvious str8 draw i think my implied odds are still ok and im good to call anyway. Thinking about how important pots odds are here, hands 67dd should propably be folded on the turn as i expect way less value at rivers with diamond flushdraws than with club ones.

River.
I decided that my 9x is not good enough for the most part and on this particular runout, if he checks, his bottom range looks like AA-QQ/AJ.
So i turned it into a bluff, i can definetely play solid amount of flushes like this.

The problem is, that i expect him to do this pretty often with KQ without a diamond or JJ/TT/JT as its difficult for him to find another vbet on this runout where he simplsy lack bluffs. For same reason he's propably not shoving all of his flushes there and ch/c some of these.

So his checking range for the most part should look like:
24 combos of AJ/QQ+,
24 combos of KQ/JJ/TT/JT

I risk ~14$ (his stack) to win 36$, so i need 36% FEQ. Which, even adding some of flushes to his range, should still be ok to turn my hand into a bluff, as i expect to win close to none after checking it down.

(to simpify things im assuming he's calling most of his KQ/JJ/TT/JT and he's folding AJ/QQ+ for my shove, but in reality he's or he rather should call mix of all these looking mostly for diamond blockers?)