Loose universal joint(s) in drive train.
The simplest thing to check would be the universal joints on your drive shaft. See if you have any play in any of those universals. The springs in the center of the clutch disk could also be out and cause a clunking. MGB's also have thrust washers in the differential that wear out and cause a clunk in the differential.
Are you sure it is the transmission that is clunking? It could be the u-joints on the drive shaft that are making the noise. When the u-joints on the drive shaft are bad, there is an audble clunk when you accelerate and when slowing down (basically the same motions you go through when shifting gears).
It could be that the transmission fluid is low, or it could be that mechanical parts have worn down. If so, it may be time for a replacement.
They could squeak, rattle, bang , clunk.....
Check the transmission fluid level, be sure it is at the full line. A worn out universal joint could be the source of the clunking noise when the transmission is shifting.
no, check your fluid levels.
A transmission that is sticking would cause a 1997 Plymouth Grand Voyager to die after shifting it into gear. A problem with the ignition system could also cause this.
Bad alternator
check the exhaust system
Hey Dee ann==Not simply idleing the engine. If you had an extra load on it to cause it to overheat this could cause it. GoodluckJoe
Could be a bad throttle body
A seal is going bad, trans will need a overhaul.