97 4x4, 4.0, auto. 5 inches short arms

I'm getting a loud shudder/revolution thud(fap fap fap) when I accelerate from a stop at normal speeds for the first three gears or close to all three. If I mash the gas no noise.

Also at normal speed on the road she sounds louder.

So far I have checked.
1. ubolts are tight to specs
2. ujoints in the rear are tight no slip in the cv drive shaft. (HnT)
3. front drive shaft was removed today( after noise started) and ujoints looked good.
4. T case fluid and linkage are good and tight
5. Tranny mount is tight and fluid is good and full

I was going to check the flex plate bolts up next to make sure they were tight.
Feel free to throw your 2 cents all over the thread.

 

after the overwhelming amount of interest in this thread I thought I would update.

Last night I had the rear end up on stands and she sounded good while spinning her. Turned her on, the rear end was still good but the faping was coming from the transfer case or rear drive shaft. S withed the rear shaft and all is better no no noise. So for now i'm happy

 

So there was a problem with the rear driveshaft? What did you do to fix it?

 

I put the front drive shaft in the rear and i'm getting a new drive shaft for the front from the jy.

When I hold the bad drive shaft in my arms it moves and seems fine.

I would rather just get another cv driveshaft then spend the money at a shop to fix this one.