Hi,

It’s been my experience that a high pitched shrilling sound, at speeds above about 50 mph, to be usually a center support bearing on the drive shaft.
I have only had one go out so far on my cars and it was also a wagon but of 1986 vintage and it was the ball bearing gone dry. The balls want to slide and not roll.
I can’t say if the later wagon cars changed any, but the sedans have them too.
I can’t say if the lengths change much but the loads can.

On my 1986 I have a low speed (10-15 and up to 20 mph) chirp that has been chirping for a long time.
I have pulled the drive shaft recently to at least change the rubber support and inspected the bearing and feel out the universal joints.
Al was smooth and in normal fit yet the chirp prevails right back up to its normal level of sound.
I think I’m headed for new joints.
At 350K I must have changed out one, once? To many years ago to remember.

A year goes by so fast that I try to relate to what the was season was when I last worked on a car and at which house.
The season’s are start into blur together at my age.
I try to keep a log on each but that takes another discipline.
I have not been good with getting that in line with other ever changing priorities.

I’m pretty sure it’s got to be something in driveline but it’s far from being dangerous.
It just reminds me that its that one, of my six cars and not to forget about it totally.

The chirp will probably change into a shrill eventually.
You know, it’s like the proverbial little bird on the shoulder, that you don’t dare not to listen too.
Birds can do more than just make a noise on your shoulder. (:)

Phil