Mystery Vibration

So this weekend my truck developed a weird vibration that I've never felt before. Its worse when the truck is loaded and vibrates at around 35, 50 and 65 mph when accelerating. As soon as I let off the gas, the vibration subsides. It feels like a carrier bearing maybe, but I'm not sure how to definitively tell. I was going to start eliminating things by having the balance on the tires checked, then move on to the more menacing idea that it might be a driveline issue. There is only about 1/4" of play in the rubber bushing around the carrier bearing.

I read thru this post, which seems to make sense for how to adjust angles, but I'm wondering why this wasn't an issue before now and suddenly I need to adjust driveshaft angles.

https://www.tacomaworld.com/threads/drive-shaft-vibrations-solved-step-by-step.244535/

Any ideas of what else to look at before I go shimming away at stuff would be greatly appreciated.

 

"ONLY 1/4" PLAY" on a decent mass rotating several thousand revolutions per minute.

Your truck is now at least 5 years old, your carrier is toasted man, if you changed nothing and suddenly you have a vibration then something has failed.

I'd change the carrier bearing first, 1/4" is a LOT of play for a part intended to keep your driveshaft from moving.

Shimming and changing angles is for after you lifted or changed some aspect of your truck, changing angles when nothing else has changed is only going to compound your issue and make it hard to resolve when you finally do change your carrier bearing.

 

https://www.tacomaworld.com/threads/vibration-diagnostics-for-all-tacomas-write-up.520607/

 

carrier bearing when you put the new one in fill the empty donut with black silicone /poly.

 

The vibration is worse when loaded ?
This means you are adding weight to a possibly sagged out set of leaf springs which in turn increases your driveshaft angles . Can you confirm your leaf springs are still good ?
Not saying the carrier is in prestine condition but this is Tacoma World and you are a member here now which opens you up to a wealth of knowledge .
Did you go through the link that was posted above ? There is 60 years of vibration diagnostics attributed in that thread not only from myself but members with 50 years operating Toyota trucks . do some research so we can save you some cash$
Have your universaL joints been greased at every oil change ? Pay close attention to the rpm when you feel the vibration , not the vehicle speed . Judging by your explanation , my first guess is a faulty universal joint .