Truck thumping noise diagnosis

[Hummer]

Hoping to get suggestions about the source of a rhythmic thumping noise that I'm getting from my 2003 Tundra. I can hear and think I can feel the thumping from the undercarriage somewhere. It's not very loud and it gets faster as the truck speed increases. It sounds to me like a pump knocking. Crawling underneath, the U-joints seem tight but there's a drive shaft center support bearing where the shaft has some play, maybe 1/4-3/8 of an inch. I don't know if that's normal. It's in the center of the picture.

The transmission seems to function fine and the exhaust system is tight. Perhaps it's another bearing, mount or bushing. What do you think? I've scheduled an appointment with the Toyota dealer service for next week. If it is the center support bearing, it would seem to be a simple fix. How serious is it? Can I tow a trailer to Grand Junction and back before fixing? What am I looking at for cost? Would a non-Toyota brand part work as well and would an independent shop be cheaper?

[Irving]

I don't have your answer, but can you be more specific about when you hear the noise? It sounds like all the time. Is it correlated with RPM, or wheel speed? Does acceleration/deceleration, or shifting affect intensity?

[BPTactical]

Center support bearing is collapsed, its plain as day in your pic. There should be no appreciable movement on a center bearing.

[BushMasterBoy]

Have you tried jacking up the rear and putting it on jack stands? Chock the front wheels and have someone rev the drive train some. See if you can see the source of the vibration. If the center support bearing wobbles it is probably the rubber has lost its firmness. Watch the wheels when they spin, a wobble could show pothole damage. Or a bad axle bearing. Make sure the drive shaft has not lost any welded on balance weights. Make sure no differential seals are leaking oil. Hope this helps. The bearing is removed and replaced by only two bolts. Should take less than an hour to R&R.

[Mykidsdad]

Did you check tires for defects?
Check tires for balance? Maybe you lost a wheel weight?

[00tec]

Yeah, that carrier bearing looks off center to me. Probably time for a new one.

[Hummer]

Thanks everyone for your suggestions. I'll let you know what we find.

[Irving]

Get it figured out?

[Hummer]

They tell me it's the limited slip rear differential. Not cheap. I've hauled a lot of heavy loads with it. The truck has 220K miles but I'm not ready to buy a new one. When I do my plan is to make this one into a snowplow rig and sell the '85 SR5.

[Irving]

That sounds suspicious. Have you had a second opinion?