arkansas dave

recently noticed my wifes 2000 expedition 4.6 2wd has a weird bump/lunge at low speeds it sounds kinda like bump on the tire about every one revolution of the tires and jerks forward and then back kinda like when you shift a 10 speed bike and the chain slips for a second until it engages this happens on when going under 10 miles per hour like in a parking lot or in the driveway but it is a real noticeable thud you can hear it and feel it. I looked at the u-joints and they seem extremely tight it has 75,000 miles on it. I did notice the output shaft has about a 1/4 inch play up and down when you shake it but the transmission shop I use said that is normal for that vehicle. I am not sure what the deal is I just hate replacing parts to fix it if I am not sure what it is to begin with. Any ideas would be appreciated.

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arkansas dave

I drove it again this afternoon and it only does it periodically it isn't consistant.

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anniejrt

i had something similar on my '97 expedition-noise in the rear end and when backed out of a parking place or was going around a turn, it felt like I was going over a cobblestone road. 2 or 3 times if I'd go over a bump, it felt like the rearend skipped. took it in 4-5 times, explained it and they found nothing. finally had a tech go with me for a ride to feel/hear it. they did some work in the differential and replaced some geras/bearings. fixed now!