I just bought a used 06 ram quad cab 4 x 4 4.7 ltr to tow a TT weighing about 4500 lbs. My question is..when towing, the engine sometimes gets real loud but the rpms dont go up. It seems when i press the accellerator it revs but doesnt show it on the rpm gauge. Sorry for the lack of more info but im new to this. It happens mostly when climbing if that helps. Is this normal?

Fish,

When climbing the only loudness I could think of would be the engine kicking into a lower gear. Especially if you are pressing the gas pedal down further. Does the vehicle go into a lower gear when the "loudness occurs"?

It stays in the same gear and just gets louder. Even when I stop and then resume it is just real loud. Then just goes back to normal. Is my transmission over heating or something?

I had an 04 4.7L and I towed a similar weight RV. On hot mountain passes, the same occurred. This is the engine clutch fan engaging and disengaging. The fan always spins, but as your engine/coolant temp goes up the air going over your fan assmebly heats and the clutch engages so the fan spins at higher speeds to increase cooling. You hear it as a loud roaring sound, and probably also notice a small drop in power (at least I used to).
You may also hear this sound when starting your truck when its very cold, as the clutch in the fan needs to spin a bit to warm itself before working correctly (anywhere from 30sec to a couple minutes).

Its all perfectly normal and nothing to worry about.

Thanks for the lesson, I needed to hear that