98 Ford F-150 4.6L Auto trans concern. Ford techs?

I know this is a mustang tech forum but I see some actual ford techs on here so thats why I am asking here.


Hey guys My chick friend has a 98 ford f150 with the 4.6L and the 4speed automatic tranny. My concern is the noticeable clunk that the truck has when the trans shifts from 3-4 gear (at normal cruising speed) or when pushing the gas down in 4th thus making it kick down to 3rd. It only does it between those two gears too. The 1-2, 2-3, shifts are great and smooth but as soon as it shifts into overdrive it clunks alittle bit and when it kicks down from overdrive to 3rd? When you sitting still and switching from P to R to D it clunks alittle. Can someone help me figure this out. I am a Chrysler tech in a training and I need all the help I can get. So if you guys could help me with where/what I should check first and the diagnostic procedures I should use to determine this problem. I will be in debt to you if anyone can help.!

Thanks man I see what I can find out!

I was playing around with it tonight and heres what I've come up with.

When I was sitting at idle and went from Park to Reverse or Drive it would clunk alittle as it shifted to either R or D. So after that I got up under the truck and examined the u joints and didnt notice anything out of the ordinary. So I started to try pushing and pulling on the driveshaft to check for play. The rear Joint didnt have any at all but when I moved to the front it seems to have a slight little bit of play in the u joint. No much but alittle. U joints arent suppose to have any movement at all right? Could even the littlest movement cause a clunking sound?