Pulsing sound in 5th gear

[Tyler]

Hey there, new to this forum. I have a 2015 ram 1500 express 4×4 with 58,000 miles. It’s the 5.7 liter with an 8 speed tranny. A couple weeks ago I noticed a pulsating sound and reduced it down to only happening in 5th gear. I feel a very slight vibration in gas pedal. I can hear it best when the engine is under constant load going up a hill and as the rpms rise (starts around 1500 rpm until its shifts around 2000, unless entering the freeway and the rpms get higher before shifting) the pulsating gets faster until it shifts and the noise disappears. Shifting is smooth in to and out of 5th. I also don’t hear it when the rpms go through the same range in other gears. All temps are normal.

I do have it going in next week for what I believe is a broken exhaust manifold bolt or bolts and for them to check out the pulsating sound. Could the pulsating be connected to the broken manifold bolts in any way (exhaust leak?), and if so why would I only hear it in 5th gear? Or is this a transmission issue? Just trying to figure out my next move if the dealership says they can’t or won’t do anything since there are no codes popping up. Any suggestions are appreciated.

Thanks

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