Transmission clunk-Not normal?

[SPICER]

For some reason I cannot reply to the previous thread, so I will start a new one.....

When I am decelerating(braking or not, does not matter), I hear a clunk like a gear locking in. It happens predictably at exactly 18 mph and can only be heard with the windows down. It is louder if I am decelerating quickly. I do not see anything on the tachometer at the time. I hear the same noise, only louder, if I am in reverse going 15-20 mph and let off the gas quickly. 14k on a 2003, tranny fluid good, any help? SPICER

[SPICER]

Is it my breath? why no replies???

The sound is more like a loud click, like it is downshifting and locking in. I just want to know if this is normal. This was described under a different post recently, but the result at the dealer was not described. Any Help? Anybody? SPICER

[a64pilot]

Try removing the driveshaft and lubing the yoke (on it's inside) that inserts into the tranny. I have heard of similar noises that were cured by this. Their noises were similar to worn U-joints

[SPICER]

I read other posts that the clunk was upon take-off and stopping. mine is while decelerating and exactly at 18mph. The only other post that I have seen describing this exact condition is Catalina455 in a thread with the same name "Transmission clunk-not normal" This was in April, I'd like to hear his resulys at the dealer. SPICER.

[JEBar]

Had a start off clunk in my 3500 crew cab's drive line that was caused by movement in the joint where truck's 2 piece drive shaft is joined ... dealer had to end up replacing entire shaft to correct ... I see you have a 2500 crew cab so I don't know if the same could apply to your truck ... mine only "clunked" when taking off from a standing start so may be an entirely different problem ... Jim