[rbenuck4]

Since there are a bunch of limpers and he checks his option in the BB and doesn't go nuts on the flop or turn, I think we can rule out a big pair like AA KK or QQ. I also don't think a decent player would make this move with a 10 because he will only get called by a hand that beats him. Therefore, I believe the two hands that are possible are pure bluff or the 3. now we have to figure out which one he has.

Since you mention that he has noticed that you like to overbet pots on the river with strong hands, and while you didn't over bet the pot, you put in a good chunk of it (about 90%), he has to put you on a hand. I think if he had the 3 he would've played it differently on the river such as betting out. There is 2680 in the pot and it costs you 1500 to see it, so you are getting a little bit less than 2 to 1. I think that's about right for a call here.