my 90 LS has developed a weird phenomena.
at highway speeds the rear literally feels that it's going to give out when changing lanes. kind of like a boat. i believe it's called fishtailing...
what bushing/part would i need to replace to correct this ?
thanks.

 

How are your tires doing? Have you done an alignment check?

 

tires and alignment are goood.

 

alignment is not good...

guarantee it... it might be sitting OK while on an alignment rack, but my bet is that you have some worn bushings somewhere... if any suspension bushing is worn, then the alignment is completely inaccurate...

so, have a good tech take a peek at the bushings, front and rear... have the bad ones replaced, and have the car aligned properly...

 

He's right, check the rear lower control arm bushing. The bushings located on the very bottom of the rear knuckle. You can buy the bushing for $80.00/pair.

 

have the rear control arms replaced. issue exists. Loud thump noise when going over bumps or through minor pot holes etc. noise is coming from rear. Struts are new. control arms new.
any ideas ? had alignment checked again came out ok.

 

Rear strut bar bushings. Although if you have any worn bushings, a good tech will see them and tell you during the process. Getting a good alignment is near impossible. How are the tires wearing? Cupping?

 

We cant diagnose stuff over internet. Get an oil change and ask them to look at it. Im guessing the sway bar link is bad or broken.