Rediculous Clunking in Driveline

[slravene]

After I've been running for a while at speeds (60-80mph) I'll be going along with my foot on the gas (Highway) and if i take my foot off the gas completly and quickly, there will be a loud CLUNK from somewhere in the driveline (tranny or tcase i believe). However if i ease off the gas it will not make this noise. 120K on the odo. and this is boggling my mind. For the 4wd guys it sounds kinda like the sound when switching from D to R while in 4wd under trail conditions. Help if you can. Thanks.

 

[mechanix]

Sounds to me that you might have a u-joint loose. That would be the most common thing I would assume. Other causes could be excessive ring and pinion slop, pinion bearing,drive shaft slip joint, tcase chain (I am not sure on this one, I have never been in a 1354 case).

Keep us posted.

 

[slravene]

how should i go about checking/diagnosing those issues?

 

[wired_af]

Read this and see if it helps:

Diagnosis of Driveshaft and U-Joint Problems