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My 1994 Fleetwood (185K miles) has developed a booming noise that you can hear at 31-35 mph and again at 61-65 mph. The noise is the same whether accelerating, cruising, or coasting (in drive or in neutral). First noticed the noise after the transmission was replaced. Have replaced tires, u joints, and have had drive shaft removed and balanced. Also had differential checked.
Transmission was replaced again under warranty. Any suggestions??

Checked that everything is tightened down? Ie, any of the insulation panels around the tires, etc. And Booming?....

What do you mean by booming.

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My 1994 Fleetwood (185K miles) has developed a booming noise that you can hear at 31-35 mph and again at 61-65 mph. The noise is the same whether accelerating, cruising, or coasting (in drive or in neutral).

Does it get faster or slower, louder or softer? Or constant same noise?

Sounds like an exhaust drone. Did you change exhaust?

I bet one of the motor or tranny mounts are loose. That or you have a differential problem. Maybe the Axle U-bolts. Tighten everything up.

Checked that everything is tightened down? Ie, any of the insulation panels around the tires, etc. And Booming?....

Haven't found anything loose like that. The"booming" is a resonance that begins at 31 mph and is gone around 36 mph and the returns at 61 mph through about 66mph. Otherwise the car is Caddy-quiet. I have owned this car for 10 years and plan to drive it another 5 or so. Would really like to find the problem.

What do you mean by booming.

It is an annoying resonance that starts at 31 MPH and remains through 36 MPH. It goes away until I hit 61 MPH and it goes away at about 66 MPH.
The car is Caddy=quiet the rest of the time. I drive this car to work every day and this problem really detracts from an otherwise enjoyable car.

Does it get faster or slower, louder or softer? Or constant same noise?

Sounds like an exhaust drone. Did you change exhaust?

It is about the same but only occurs in these speed ranges; 31-36 mph and 61-66 mph. I have not changed the exhaust as everything looks okay from the outside. I have wondered if a muffler or resonator could have something loose inside causing the problem.

I have been hoping to find someone who has experience the problem.

I bet one of the motor or tranny mounts are loose. That or you have a differential problem. Maybe the Axle U-bolts. Tighten everything up.

Could be. Will give it a try. Thanks!

I have been hoping to find someone who has experience the problem.

I have never had (or heard) the issue. But I have been researching B-body aftermarket exhausts and some are prone to create droning sound.

Maybe your exhaust or resonator deteriorated to cause this phenomenom?

Does it come from the rear or front or?

It seems to come from the rear. I was sure it was in the driveline, but checks of flywheel, torque converter, transmission, differential, replacing u-joints and tires, plus balancing the drive shaft have not corrected the problem.