4 speed automatic whistles?

I have an 06 Tacoma 2 wheel drive with the 4 speed automatic and it's got 26,000 miles on it. Around 20,000 miles the transmission started to whistle when it hit 55 miles per hour. Now not only does it whistle, it vibrates like mad. I changed the trans oil and used the exact same stuff Toyota uses, and the filter, at 22,000 and that helped a bit, then at 23,000 it started acting up again. The oil isn't burned up and the trans temp is in top shape, I installed the trans temp gauge at 23,500 to make sure. Whats going on with my transmission???

 

vibrating when accelerating or all the time?

 

It happens all the time but if im going above 65 and let off the throttle it vibrate really something awful.
I also know my tires are all balanced. I've narrowed it down to the transmission or the flywheel.

 

OH and another thing, when it shifts into 4th gear, around 2000 rpms it starts to pulsate and the revs go between 1800 and 2200...

 

after you changed the fluid,did it stop vibrating

 

It stopped whistling, then around 25000 it started the vibrating.

 

i don't have a 5/60, its a 3/30 and the 3 is up.

 

may have a torque convertor problem..make sure to check your u joints .i think your still in power train warranty,call dealer to make sure.

 

I already tried. They said it was my fault because "As far as we know, you overloaded a trailer and did that"

 

I have checked the U-joints, they're all good. as for the torque converter, would that be causing the whistles? I replaced the torque conv in my 97 F-150 because it got to vibrating but never surged or whistled.
What gets me is..that F150 has upwards of 280,000 miles on it and thats the only issue its had

 

have you read owners manual to see what powertrain warranty is,it should be 60 k but i,m not sure on a 06. i dont think they can deny your warranty for something they think.if it's under warranty somebody will fix it.we are going through bad times in the auto industry,someone will be glad to cover that if its still under the mileage.

 

I might just tow it (have a flatbed trailer) to a different dealership. The one where I live (not mentioning names) hates me because I know more about that truck than they do. I just hope that it's still covered...

 

i work on hondas, been there for 24 years.it doesnt matter to me if its warranty or not,money is money.trust me if its in years and mileage they cannot deny you warranty work.somebody will be glad just to get the job.if i worked on toyos i would be glad to fix it for you,i would make some money,and you would get your truck fixed for free. good luck dude!