Rod knock on a higher mileage motor is pretty common, however, if you could take a video of the sound you are hearing with the hood up and share it in this thread, that might help folks to help you to narrow it down. It could also be a bad exhaust leak, too.

 

 

Well, 4 years at any rate. That's the trouble with those kind of noises, at this point, we are merely guessing. If it actually IS bad bearings, they may go out the next time you start the motor, or, they may last another 50 years.... It's impossible to tell.

 

 

Budget a custom tune in there as well then. And don't forget new heads. The stock fellers suck, and are prone to cracking.

 

 

All of this advise is dependent on your budget and time. If you have time and mechanical skills, you might consider what I did to get more life out of your truck and not bust your budget - my original 5.9 motor needed replacement due to major rust issues - I found a good used low mileage 5.9 motor off Craigslist that came out of a Dakota. I brought it home and put it on an engine stand to start doing a refurb job on it. I pulled all of the freeze plugs and cleaned out the cooling passages in the block and replaced the all of the freeze plugs with brass plugs. I pulled the oil pan and checked the bottom end. The bearings were just fine, so I put a new pan gasket on it, along with a high volume oil pump and screen and put that back together. I took my old kegger intake and swapped it onto the new motor. Also put in a new distributor, cap, rotor, plug wires and plugs. I also installed a new water pump, double roller timing chain/gear set, tensioner, belt and a set of shorty coated JBA headers (also found on Craigslist). I cleaned up the motor, painted it and installed it into the truck. It has run like a clock ever since.