This is kind of a lengthy post but this issue is so hard to explain. My 4wd binded up and I could barely even drive everything was so tight. I parked and it released in about 10 mins. After that I can go in and out of 2H, 4H, 4L and can even lock the differential with ease.

What happens is at low speed and rpms there is a vibration that sounds like I am driving over a washboard. This only happens for about 5 seconds and goes away. But it has been happening with more frequency so I am afraid something is failing. I keep reading about the drive shaft and u-joints so I jacked it up and nothing is loose. Although I did seen some fluid around the transfer case but I have never seen fluid leak onto my driveway. I am completely perplexed with what the issue can be. I have never had a any type of flush for the transmission or 4wd. Please any help is welcome.

Don't know if it has to do with binding your drivetrain up or not, but it sure sounds like this:
"Rumble Strip" Transmission issue

Had that happen to mine a while back, a drain and fill with some shudder fix solved it, drove it for a month and then had the trans fluid exchanged. Shifts like butter now.

Driving over a rumble strip is the exact description for the sound. Thanks for your advice.

ive heard that rumble strip being discussed as relative to the trans. the talk about binding before all this almost makes it seem like an axle or chassis issue, no?

If its the trans, its most likely the torque convertor when its underload which is the 30-40mph range. I put some shudder fix in mine and hasnt come back in over a month now.

When I would put my car in 4th gear, I couldnt reproduce the issue. Thats how I narrowed it down

I purchased shudder fix but I am having a difficult time getting the full plug to break. Can I use WD-40 or do y’all recommend another type of agent to loosen?

When those are on there tight I usually use one of my 1/2 impact sockets with a breaker bar. Basically cause my impacts are 6 point sockets and I get more contact with less worry about rounding off the head. Makes it easier to apply a little more torque to break it free. YMMV

Also what @bricew25 said... I couldn't get it to vibrate if I ran in 4th and wound up driving around for a few days like that till I could get to working on it. That ought to let you know for sure if this is the issue you're dealing with or need to chase something else down.

I picked up an impact socket and the fill plug broke loose. I got the shudder fix in and drove around for about 25 mins. Did not feel in shuddering or vibration. I hope this works 🤞🏽

Thanks for all of the help

Hoping not to jinx you, I'll offer a cautious congratulations!

I exchanged my fluid with new Toyota WS as catch-up PM when I bought it at 164K miles. No torque converter clutch chatter then, and none now thankfully.

I'm guessing the Shudder Fix replenishes friction modifier in the old trans fluid. If you plan on keeping the vehicle for a while, a fluid exchange some time down the road would be a good idea.

That's great @bjax4x4 !

As @waypoint said, if you plan on keeping it, I'd do a trans fluid exchange. I had a shop that a bunch of us go to do it. Gave me more peace of mind having it hooked up to a machine rather than me trying to measure out and replace in my garage. Also, I didn't have it flushed (with pressure) because of mileage, just an exchange.

I had a similar issue once, but it wasn't preceded by the 4wd locking.

I'd get a vibration at low speed...we're talking just 5-15 MPH...that drove my OCD a bit nuts. Also, it wouldn't occur at all in 4wd. Turned out to be the front differential needle bearing, which have quite the failure reputation in the Taco rooms. The OEM part itself is probably one of the least expensive pieces on the vehicle at $15 but I replaced with the East Coast Gear Supply Clamshell Bushing for around $60.

Not sure if that's YOUR issue, but if the vibration goes away in 4WD, it might be something to consider.

Good luck!

i had what i thought was the torque converter issue when i bought this v8 4r a month ago. I was getting the rumble on the way home after i bought it, at around 60-70mph though, either applying load or letting off the skinny pedal but it would go away just cruising. After further inspection, the front u-joints were shot (no needle bearings, and half a cap) I bought new spicer joints and put them in and the problem was all gone. Hopefully i dodged a bullet on that one. I went ahead and put a timing belt kit on it also while i had it in the garage since the previous owner didn't know when or if it had been changed.