this is an ae85 with a 20v svt swap. The noise is like a metallic rattle. It’s repeated so almost like a loose metal line hitting the body or chassis. (Tatatatata) Yet only does it upon deceleration and when I’m coasting in neutral as well. Not while acceleration nor idling stopped. It’s coming from under the car just can’t really pinpoint it. Can this be an unbalanced driveshaft or bad u joints?

Try checking the exhaust.

Ae85? Sounds like a heat shield....iirc there is one in the rear above muffler, one above the bend over the axle and another one above the catalytic converter......but I'm not familiar with any ae85....

Get under the car and grab the driveshaft with one hand either side of the hanger bearing.
Check for movement up down and from side to side. If the shaft moves around a lot and
easily, you might even be able to get it to "clunk" with a good heave. If it does, then that
means that the rubber support for the bearing has broken down, and you need to replace
the bearing assembly. Looks like this....



If the rubber is quite firm and you can't get much movement in any direction, then statrt
looking elsewhere

Cheers... jondee86

notnilc20 wrote:Ae85? Sounds like a heat shield....iirc there is one in the rear above muffler, one above the bend over the axle and another one above the catalytic converter......but I'm not familiar with any ae85....

It’s the same as ae86 just base model. And no this car has no shields of any kind it’s torn apart lol

jondee86 wrote:Get under the car and grab the driveshaft with one hand either side of the hanger bearing.
Check for movement up down and from side to side. If the shaft moves around a lot and
easily, you might even be able to get it to "clunk" with a good heave. If it does, then that
means that the rubber support for the bearing has broken down, and you need to replace
the bearing assembly. Looks like this....



If the rubber is quite firm and you can't get much movement in any direction, then statrt
looking elsewhere

Cheers... jondee86

I couldn’t really get good leverage since I only have a scissor jack but I got under and saw marks on the driveshaft well as if the driveshaft has been rubbing in there above the shaft. So I think you may be right with that shaft bearing.

also check driveshaft bolts are nice and tight, at the diff flange

Finally lifted it and took a look. There are markings of driveshaft scraping the tunnel above it on the chassis. What can this be?

Has to be the center bearing like kinder said
See if it moves around , grab the drive shaft move it around with your hands if moves a lot needs to be replaced . It shouldn't have any play