Something in the drivetrain!??!
 

I have an 86 Firebird with a stock 305 5 spd. Usually when the car is hot, for example, If I am in first gear and I gunn it and then get off the gas, I hear a clunk, then as soon as I hit the gas it clunks again. I've noticed today that my rubber sway bar bushings are gone on the driver's side of the car and am thinking that's the problem???? (But I'm not sure!!) Just wondering if anyone has had a similar problem!! Any info is greatly appreciated!!!

You had also better check the U-loints before your drive shaft flops off! That's no fun - believe me. Can also almost flip or roll a car if the front drops out and digs into the pavement. Been there and done that, got that blasted T-shirt. Don't need another one.

I've also heard rear ends clunk when they're getting really close to worn out.

A friend and I took y=the driveshaft out and the u joint was fine. So we know its not that. I'm just out of solutions

Sounds like the transmission mount is gone.

Jim.

Where does the noise sound like its coming from? Have a friend listen, outside the car maybe. And try not to run them over.

In line with vernw's suggestion of th rear: make sure you exhaust other options first. I had a noise that sounded like it was coming from the rear, matched the service manual's description of "Backlash clunk". Opened up the rear to find nothing wrong (I still stink!) and its a bitch to refill anyway if you don't have a lift.

Also, with similar symptoms (not identical) the service manual indicates that the slip yoke lacks lubrication. Check your tranny fluid.

From the service manual for your reference. Do the easier stuff first so as to not want to kick your own rear later. :)

"10. Clunk on acceleration or deceleration

a. Worn rear axle pinion shaft in case or side gear hub counterbore in case worn oversize.

b. Worn universal joint on properller shaft.

c. Slip yoke lubrication insufficient."