Dodge ram 2500 transmission makes noise that comes and goes.

drop off the cover under the torque converter and inspect the flex plate that the converter is bolted to. look for cracks in the plate around the bolts . undo the bolts and move the torque converter back towards the gear box and look for cracks around the flywheel bolts.. If all ok then do everything up and have a pressure test done on the transmission to check for internal mechanical failure. Have this done at an accredited auto transmission shop ( not the local mechanic) and as him what the results are and the possible solution. Remember to ask how much to fix the problem parts before you accept that it needs a new box

remove the inspection cover under the torque converter and check for failed flexi-plate drive. The plate that the torque converter is connected to that is attached to the crank shaft. Check the torque converter control (TCC) clutch solenoid/servo for failure.

Sounds like the metal shield between motor and transmission it happen to my durango I thought it w as torx converter bolt coming loose It was my flex plate bent

Depends what the rattling is really... If it's the engine , could need a valve adjustment... I've also heard of torque converters make a rattle when going bad, but only when in drive or reverse

It could be a loose heat shield on the exhaust. How ever I have seen the inspection plate loosen at the torque convertor housing. There may even be a loose bolt on the flywheel.

This mainly is caused by transmission fluid level changes. Measure it when its at running temperature and in park. Add if necessary (most likely the cause)

sounds like the torque converter has good out, very common, or a problem with the transmission

The inspection cover is usually plastic, it is bolted to the under-side of the bell-housing and it is held in place usually by 4 small bolts, and once you remove them the inspection cover should come out. (you might also have to remove the starter on some applications)

After you have removed the inspection cover most of the flex-plate and the torque converter will be exposed. Turn the engine over and use a good light to inspect for damage to the flex-plate, and also check to see if the torque converter to flex-plate bolts are tight when they revolve into a position where you can attach a good ratchet.

Your problem sounds like it may be one of two problems, the first thing that comes to mind is a defective rebuilt transmission, which is remedied by taking it back to its rebuilder while it still is warranteed, may be a bad pump but leave that to the pros to determine.
Second thing that comes to mind is the lock up torque converter, no matter what that whole assembly has to be taken down for either of the above conditions to be properly repaired and inspected.

Noises can sound like they are coming from different places , when its not. First, remove the serpentine belt from the alternator etc and run the engine. If the noise has gone , then its a pulley,alternator , pump, bearing etc , you would need to check each part.
Check the exhaust is not rattling or insecure, or the heat plate is not cracked or loose etc.Check the engine and transmission mountings, if they are cracked or too soft and making the power unit hit against the body etc
You must eliminate everything before you consider stripping the transmission.Hope that helps