truck 2005 3500 2wd no mods 5.9 liter 24 v with 120k used to pull 3000 pound race car and 18 foot open trailer
i was pulling the race car to the track last night when the truck started making a louder than normal knocking sound it seams to go away at idle but gets louder at the RPMs go up. oil pressure is 40lbs and the temp is 200. Could it be something besides a spun main or rod bearing

 

When the main bearing spun on my truck the noise became progressively louder and louder. I was towing my #6500 boat at the time it started as a "tick, tick, tick" and deviloped into a "knock, knock KNOCK" within 10 miles. There was no question that a major problem was happening in the motor. I would guess another 10 more miles longer some part of the engine would have been coming out of the block. The noise was present through the whole engine RPM range, even at idle.
That was 5 years and 77k miles ago for me. Sure hope that is not your problem.

 

Could easily be an Injector.

Figure it out and soon......... Bad things happen quickly.

 

well started the truck today to put it on the trailer to take it to the shop tomorrow and the noise has stopped , but the truck has white smoke coming out of the tail pipe. I only had it running for a few mins but smoked the whole time it was running.

 

With the CR trucks, it is very easy to kill the engine with a malfunctioning Injector.

I would get it diagnosed and fixed before you do anything else.

 

Sounds quite likely to be an injector problem!!!