Having a vibration on a 00 park ave, seems to be coming from the rear right wheel, i thought it was maybe wheel balance was off so i went n had all the tires balanced and problem is still there, has new rear struts & track bars.

Have you rotated the tires to see if the wobble moves?
I have heard of the belts in the tires breaking, or shifting..
How old are the tires?
When was the last time you had a 4 wheel alignment done?

Agree with William, rotate tires front to rear and see if vibration moves....

Once i noticed the vibration, it seemd as if it wss coming from the back right rear tire, i suspected that it was a problem with the "track bar/ lateral link" so i then replaced it on both sides, problem was still there so i installed new struts, and still was there. I then took it into firestone and had the tires balanced because i noticed one of the wheels didnt have a weight.. And they also rotated them. Problem, still the same...

They can balance the tire, but I don't think that will help anything if a belt in the tire is the issue.
It is possible the issue could be coming from the front, and you are just feeling like it is coming from the rear.

If you are sure it is the rear, and it is speed sensitive as you say, then it could be an off-center wheel or hub, your rear braking system is drums right?
If so a drum could be out of balance.
Inly way to attempt to balance for that would be find a place that has an on-car balancer to balance the wheel on the car, even then that would only be a temp fix, as eventually you'd want to replace the drum with a new one to get rid of the off balance issue, if that is the problem that is.
I'll give it some more thought after I get some sleep.

Thats what i was thinking! That maybe it was a problem coming from the front. I know i need two front outter tie rods but i dont think their that bad and a wheel hub on the front right but its like just beginning to feel bad ive had em worse and didnt have vibrations... Ive been thinking that maybe it could be something in the front suspension like maybe a bad strut.
Rear brakes are disk.. Also have beem thinking tht maybe i have a wobbling rotor possibly?

It is possible to have a vibration in the front, and have it felt all the way in the rear, the outer tie rods on my 96' PA were both bad, when I removed them that were really bad, the vibration was mainly felt in my steering wheel though.

With the rear discs I am not sure if they are warped or something, but if they were I'd think they would only wobble when braking.
Unless the brake pads are always in contact with the rotor.

I'll look for the vibration diagnosis info from my 96' PA'* FSM, I am sure a lot of it will still apply to your 97'

I'm sure you had a 4 wheel alignment after replacing all those parts......

"55" is like a magic number........more often than not, when you get a vibration at 55 or above, it is usually tire balance.

Be it, the tire out of balance, a shifted belt, excessive wobble in the tire or rim, etc.....this can happen even on new tires....

Went round and round on one car......finally we sent the wheels out to be balanced on a road force machine....problem solved....

Yeah it got an alignment after that, srry i kept forgetting to say it, but idk its driving me crazy.. Its not really felt in the steering wheel.. Thts kinda whats really making me think its a problem in the rear.. Cuz it could b vibrating and the steering wheel be smooth as glass.. But my passnger seat back shakes along with it... I wonder if maybe rear control arms need new boots

Tried to find what I could, but the actual info on vibration and diagnosis was missing from my FSM, which is odd..
I did get a few pages that you could read that may be helpful.