OUCH doesn't look cheap. http://www.agkits.com/search.aspx?find=D339
I got my main bearings for my D4400 from Off Road Equipment. They were Genuine Caterpillar NOS and good prices too. http://offroadeq.com/home.html
I replaced the rod bearing pistons and sleves two years ago in my D7e got my parts from a place in kanas city I thought was a fair price and good service. Razz