1986 4runner. 5 speed.
just had a new rebuilt motor and new aisin clutch done about a 1000 miles ago today on the free way doing about 70 MPH in fifth gear a hellasious rattle started. It only does it in fifth gear. under acceleration or with foot not even on the pedal. but once the clutch is engaged it goes away and like I said only in 5th gear. rpm's seem to not matter. just gets a little louder under acceleration. I would describe it as a marble or two shaking in a thick metal cup sound.
Any thoughts on what it is? tranny or the new clutch? or possibly motor pinging noise? you can also feel it through your hand on the shifter

 

driveshaft vibration can be felt through the shifter handle.

can you get under vehicle, trans in neutral, and try shaking/turning the driveshaft around? see if you can locate any free play, at either end of the shaft.

i wonder if a ujoint came loose?

 

Problem is, when I put the transfer case in neutral while tranny is in neutral I can go thru the gears and thenoise is heard when I hit 5th with car stationary

 

so the car is at a dead stop, which means that the driveshaft isn't turning, and you still hear the noise in 5th gear only.

the only way you could be in 5th gear at a dead stop is with the clutch in, but earlier you said that the noise goes away when the clutch is engaged?

 

said with trans in 5th and transfer case in neutral

 

thanks... so the driveshaft isn't spinning, but the trans is in 5th clear, foot off of the clutch.

this is giving me a headache, lol... could it be something simple, like a bracket loose?

since you can duplicate the problem at a dead stop, do it, and crawl around under the truck to see if you can locate the exact source of the noise.

i would make sure that the parking brake was on, and someone was sitting in the drivers seat with their foot on the brakes, tho.

 

Yup exactly. With tranfer case in neutral. My guess is bad rear tranny bearing or loose nut

 

long shot here... i recently pulled my trans, to put dual sticks on the rear case.

i noticed that the spring holding the clutch arm to the ball, inside the bell housing, was really loose, and i had to spend some time trying to figure out how to bend the wires around to take up the slack again, and yet not spring free from where they were held down in the clutch arm.

you can inspect that area from outside, by pulling the boot back off of the clutch arm... if there was slop in that area, it would be taken up when you pushed down on the clutch.

 

No rattling in reverse, when you do it with t-case in N?