fairly new to this 1/3 game. was surprised everyone was playing pretty tight.
sb in this hand seems to play pretty tight. have seen him check behind with 2pair on a non-scary board. my thought was that he was playing scared money.

In this hand i am on the button with 73dd.
two limps up front and a raise to 6.
from the way the first two called i was fairly sure they werent limp raising.
i call the 6 and sb and the two limpers call.

flop comes out : K 8 4(ddd)
Limps to original raiser you bets 12; i raise to 37; sb calls after a little hesitation. better folds.
turn is : 8
he checks; i check
river is : off suit 2
he quickly leads out for 65
i?
i know the flopped flush is really strong but against this player I cant find a hand for him, given how he played preflop, that doesnt have me beat.

First of all I fold preflop.

He could easily have the lone ace of diamonds.
I would have bet the turn for about $70 intending to fold if raised.
As played I think I call here.

def important that sb only had about 100 left on the river
ya i know, speculative call.
was pretty sure no one was going to raise behind and on the button
no bet on the flop,
after he check called my raise im pretty sure his hand is big where king with ace or high diamond or a lone ace is at the bottom of his calling range. i check behind to keep the flop small if im potentially already dead.

Pretty much agree with this. He is turning Ad into a bluff enough to merit a call. But you get to pretty much the same place by betting the turn and take away odds for the river draw for another diamond. If he's going to semibluff reraise with Ad on the turn, he's better than I.

as played, this is a super easy snap call.

There are enough hands the bet here as a bluff to make a call +EV. Similarly, there are hands that some villains would bet for value that you beat like top pair or the trip eights.

on occassion, villain will show up with a nut flush or even full house. Meh, it happens.

But 80% of the time in this situation, you are snapping off a bluff or a villain who got too fancy and decided to value bet his top pair or trip eights. I see it all the time at this level.