driveshaft balancing

[dagenham]

We dont really seem to have a driveline spot I'll put it here and if the moderaters wish to move it they can.
I am actually working on the wife's '91 5.0, but the idea is the same. I'm trying to find a vibration problem that I think is in the driveshaft. I replaced the u-joints, but it didnt make much difference. The car has had a slight vibration ever since we got the car. I noticed today when I did the u-joints that there is a washer tack welded to the driveshaft.
I have never seen a washer welded to the d/s from the factory. Everytime I see them it is a thick piece of square steel welded on.
My question is, has anyone ever seen a washer looking thing like that on a driveshaft from the factory???

[brsvo]

No experience with that but back in the day I had a problem with a bent driveshaft from a tire change lift issue. Was hard to diagnose.

[svopony]

more questions need to be asked before diagnosing.......

is it there all the time......... during acceleration .....during constant speed ...... or during deceleration

[dagenham]

It starts to get noticable at about 50mph. There has been two different sets of rims and probably 3 or 4 sets of tires, and it never changed any after that, so I was able to rule that out easily. It was there during accelerating and decelerating but is gone now with the u-joint change. The cross on the one u-joint was messed up.
I did goof and put the front yoke back on 180 degrees off from where it was before. I am not sure if I want to bother changing it around or if I am just going to let it go and have the d/s rebalanced(which is something I was thinking of doing anyway).

[DaveS]

Several years ago (probably 15 or 20), I had a driveshaft balanced from my '66 Mustang. I had it done at a Truck Service Center and the cost was about $40 way back then (which I thought was very reasonable). It took care of my vibration issue. Barry is right though.....