The Nissan Path

Hi folks,

I have a 2000 SE, 3.3litre, 4 wheel drive. (has about 170,000 miles on it)
Like the title says, I get an intermittent slight clunk or knock, sometimes accompanied by a vibration that stops after a couple of seconds, as I accelerate more, or let off the gas. It doesn't do it all of the time, but I think it does it in 4 wheel drive, as well as 2wheel drive, where it spends most of the time.

I thought it maye be the rear drive shaft U joints, so I replaced those. Old ones looked good anyway, lots of grease, not sticking or anything. When I put shaft back in, and drove for 30 minutes, I thought I had it beat, but then it started again....

Could the front shaft U joints make the truck clunk / shake when applying the gas in 2 wheel drive??
Or, is it more likley the torque converter, or something else??

Any help would be appreciated!!

It doesn't seem to clunk, or shudder as bad, when the tow button / overdrive off is on. This is making me think it may be the torque converter.
If anyone has seen this before, I would appreciate any advice!

I've seen this before with other car manufactures where the trans fluid hasn't been changed when it goes bad. It can cause the trans to jerk upon acceleration. Usually if you get a fully trans flush it will be ok; the torque converter usually won't jerk if it's going out.

Is it common to do a transmission fluid flush, on a high milage vehicle?
I think some believe that this can cause other issues to appear. Any feedback would be appreciated!

A full Trans service is kind of touch and go if the fluid hasn't been changed in over 100k, usually for high mileage vehicles I do a pan service in which you drain the trans pan by removing it and replacing the filter and gasket. It doesn't replace all of the fluid; it leaves about 3qts. behind which will act as a friction modifier preventing slip while at the same time you have new fluid which has alot of detergent in it and that will clean the system out. This will help with your shifts and fuel mileage.