2nd pair on the river and I shove, how thin?

[STARSCREAM.]

<font color="purple"> I had seen 2 hands from this player so far, one he called an UTG open from MP, when the flop came JKx, UTG checked, and he bet to take it down.

Second hand was vs me, he limped UTG, I raised to 6 from the BB, he called, flop was J64r, I bet 80% the pot and he min-raised me, I had nothing and folded.

I was running at about 18/15 at the time of this hand, and from the minimal stats I had of him, he was about 40/0/1.5

Once this river hit I really had no idea where I was at and just decided to shove it in (note my river bet puts him all in). </font>

Full Tilt Poker, $0.50/$1 NL Hold'em Cash Game, 4 Players
LeggoPoker Hand History Converter

UTG: $79.15
BTN: $107.70
SB: $119.60
Hero (BB): $100

Pre-Flop: A[img]/images/graemlins/spade.gif[/img] T[img]/images/graemlins/club.gif[/img] dealt to Hero (BB)
UTG calls $1, 2 folds, <font color="red">Hero raises to $6</font>, UTG calls $5

Flop: ($12.50) 7[img]/images/graemlins/diamond.gif[/img] T[img]/images/graemlins/diamond.gif[/img] 8[img]/images/graemlins/heart.gif[/img] (2 Players)
<font color="red">Hero bets $9</font>, UTG calls $9

Turn: ($30.50) K[img]/images/graemlins/heart.gif[/img] (2 Players)
<font color="red">Hero bets $23</font>, UTG calls $23

River: ($76.50) 3[img]/images/graemlins/diamond.gif[/img] (2 Players)
<font color="red">Hero bets $44</font>