1969 Rear end humming

[blinkey]

  I got 355 gears and I hear a humming in the rear end on acceleration. 440 car, can the gears be adjusted or do they need to be replaced??

[ws23rt]

Is the humming only felt on acceleration?  Is it in all gears?  Does it change when going through a curve?  Does it seem to be speed (mph) related?

[blinkey]

    Im at like 40 mph and the hum starts. When I let my foot off the gas it stops

[Chargen69]

i have the same thing, at an even pull at any speed.  speed up or slow down and it goes away

[ws23rt]

Does the humming keep getting worse as speed increases?  How is it at 70MPH?

[ws23rt]

i have the same thing, at an even pull at any speed.  speed up or slow down and it goes away

Your case would lead me to suspect the driveshaft balance as the issue.

[blinkey]

   At 70mph its not there. Its there at a slow acceleration 30 to 50. Anoying and also has a vibration at 60 so maybe it is the drive shaft. I guess what Im askin is can these rear ends be adjusted cause I heard this

[ws23rt]

  At 70mph its not there. Its there at a slow acceleration 30 to 50. Anoying and also has a vibration at 60 so maybe it is the drive shaft. I guess what Im askin is can these rear ends be adjusted cause I heard this

This sounds to me like a drive shaft balance issue. The drive shaft is long and flexible. If it is in balance it still has flex/sag. Some drive shafts may be more limber/flexible than they should or need to be.
When a good driveshaft shop spins one up for testing they should identify and correct vibrations that would be found in the range (shaft rpm) that we use them.

[ws23rt]

  At 70mph its not there. Its there at a slow acceleration 30 to 50. Anoying and also has a vibration at 60 so maybe it is the drive shaft. I guess what Im askin is can these rear ends be adjusted cause I heard this

If the vibration is from the drive shaft.--(IMO it is)-- their is no improvement to be gained from attention to the rear end.
The possible rear end causes for vibration do not fit with what you are asking about.

[Just 6T9 CHGR]

Aftermarket gears?  They tend to be noisier than factory sets.  You will get a little gear noise with aftermarket sets

Generally noise on acceleration tends to be gear sets that are worn out already & cannot be adjusted (unless this is a fresh rebuild with very few miles on it...id estimate under 50) then you might be able to recheck the backlash etc.

Noise on deceleration could be the pinion bearing preload has loosened..

[Dino]

I've had the exact same issue with my 2.96 gears.  Humming under acceleration that goes away when you let off or at higher speeds.  There's not much you can do about it but checking backlash doesn't hurt.  It's just worn out gears probably.  I put several thousand miles on them without issue though.

[Chargen69]

Does the humming keep getting worse as speed increases?  How is it at 70MPH?

yeah it is the same whine or hum at any even speed

[John_Kunkel]

At 70mph its not there. Its there at a slow acceleration 30 to 50.  Anoying and also has a vibration at 60 so maybe it is the drive shaft. I guess what Im askin is can these rear ends be adjusted cause I heard this

Classic gear noise, I've got a 3.55 489 just like it. Once the ring and pinion gears have been run for any length of time they can't be adjusted to mitigate the noise.

The vibration at 60 is a separate issue unless the rear yoke is loose.

[Hard Charger]

I had a similar problem in my stock 68.

I readjusted the axle lash and the sound ended.

[blinkey]

   I think thats what I will try. Theres a great rear end guy here in town. I will let him look at it and get back to you.