Bought my 99 F250 LD a couple of months ago and had the bucking/shuddering problem out of the gate. Was worried that it was transmission. Noticed that the problem went away when I took it out of OD. I read Bluegrass' comments on another thread and had a sneaking suspicion that one of my coils was the problem. It finally threw me a code this week telling my that my number 3 cylinder was misfiring. I took it in for a tune up today and told them to replace the #3 coil pack. When they got in there we could see where #2 coil pack was broken. Replaced both #2 and #3 and it resolved the bucking. I dove home on some hilly roads where I would always experience the bucking if I was in OD. I had adjusted my driving habits to try to avoid the bucking in the past but I just drove as I normally would on the hills in OD and no more bucking. I even tried to make it do so by giving light throttle between 45 and 60 while going uphill in OD and no more bucking.

Problem solved.

Thanks Bluegrass.