The rear end in my71 that, I drove quite spiritedly for over 20 years, didn't howl or clunk. All the clunks and vibrations were eliminated with u-joints, drive line & half-shafts, many times. Maybe I just got lucky & got a good one. I certainly wasn't easy on it & it was probably the most neglected item on the car. Mark

Now I'm curious if the 260 is going to howl or clunk when it goes on the road. Damn, I've got enough to think about as is.

Edited August 14, 201410 yr by Mark Maras
after thought

I just changed my rear diff from a 3.90 to a 4.11 LSD. The 3.90 was a little loose and clunked some, but it was a spare so I didn't care. I had the 4.11 rebuilt and put it in a few days ago. The new one has no clunk at all, and there is a whir that accompanies it...until about 55mph and then it howls like an opera singer. It stops at around 65. I know it's all super tight as it's new, but I'm wondering if it'll ever go away. Anyone else broken in a new diff before?

I also seem to remember that the tranny had a whine in it at about the same speed in 5th gear, and I'm thinking maybe the tighter diff is making the tranny whine worse and that's what I'm hearing? I'm still breaking in the diff, and it gets pretty danged hot after just a few miles so I'm not going very far. My thinking is to take it for some more shorter rides and not use 5th to see if that changes anything.

It also has the solid mount to the tranverse link...maybe some cushion in there would help, too?

no clunk lots of whine in mine.