my 99 2500 auto is showing signs of turbo coking,(does not spin freely,) also, been loosing boost at lower rpms, anyone got any suggestions as to what turbo,(stock,used) to replace it with, that will add a little more boost, I have a contact in salt lake city that will sell them at 300 for a warranteed good used one, my 02 3500 6 speed would make 35-39 lbs boost, but i dont know if that turbo would be a good replacement ,any ideas?