while driving down the road in 4 hi at about 25-30 mph i keep hering a clunk especialy whene i slow down and then speed up and i also heer it slightly while staying at a steady 45 mph its really freaking me out

 

why wont anybody reply?

 

It might be your u joints going bad. I had the same problem in my 98. I found the rear U joint was shot.
I had them both replaced and now it's fine.

 

Noticed you are drivin in 4wd when this noise is present. Were you driving on pavement, or off the road?
When drivin on pavement, the driveline can clunk. try it off the pavement, dirt road or field to see if it happens.
also take it out of 4wd to see if the noise is there. that can help us to help you in your driveline diagnosis.

 

yes i was driving on the pavment whene i herd the sound. also whene i take it out of 4 wheel drive i dont her the nois any more

 

can you
go to "user CP" and fill in some of the information so we know what kind of truck you have
it helps to know, because of model specific common issues.

 

I dont know where user cp is but i have a 2000 f150 xlt and today i was driving in the snow for some time and it seems everything everything locked in and i didnt here it anymore and it drove sweet all i can figure is that one wheel kept trying to lock in and and wouldent do to the way the the tirers wer positioned and whene i backed up and turned they locked???
I dont know???