Help...serious tacoma problem

So I was driving the other day and out of no where I hear this loud roaring/scraping sound somewhere underneath my 98 single cab tacoma. It sounds like something metal spinning and wobbling back and forth. I started with my rear end which is a dana 70 that I swapped in 2 years ago. Took it completely down to an empty case swapped all seals/bearings....that wasn't the problem. Next I went to the transmission and decided to drop it since I needed to do the clutch and the rear output seal anyway,thinking maybe the flywheel could be loose. I also changed both rear driveshaft u joints. I got it all put back together day and it didn't do it at first but then about 5 minutes into the drive it started again. It only makes the sound above 40mph while coasting the moment I put pressure to the drive train through acceleration it stops....... Any ideas, I need some help before I spend all my money.

 

Do single cabs have a carrier bearing? If so maybe that's it.
Welcome to TW btw.
If you get a chance look up member Alfuh, he's stationed at Eglin.

 

Is there play in the wheel bearings?

 

Are your hubs locked? See if it go's away in 4WD.

 

Bearings are good I checked those too, hubs aren't locked all that checks out, luckily the reg cabs don't have carrier bearings, I hate those things. It just happened out of nowhere one day, it's pretty annoying and unusual. Out of 4 toyota 4x4 trucks I've owned I've never had this problem.

 

I was thinking today, that it my either be a pinion bearing issue or a driveline angle issue. My theory is that when I accelerate my pinion is turning up at the flange due to drive train pressure, and the sound stops, then when I coast the pinion flange falls a few degrees due to decreased pressure causing it to make that sound. I'm still stumped, it's never made this sound which is why I'm torn between a pinion bearing or a driveline issue. I know somebody has had to deal with this before.........

 

Found the problem. Rear end backlash is out of spec. Pinion gear contact was off.

 

nice man, glad you found out what the problem is