waves of vibration

[Btnmashr]

I recently had my transfer case rebuild and rear main seal replaced. When I got the truck, a 97 Ford Explorer, back it has now got these strange waves of vibration every second or so. It becomes noticeable over 50 miles per hour and only goes away if I let off the accelerator. Is this part of the transfer case being rebuilt or is this part of the drive shaft? And would rebuilding my transfer case affect the drive shaft?

 

[RangerX]

Welcome,
One potential cause that comes to mind is, whoever did the work could have slid apart the driveshaft, then put them together again but out of phase, which would unbalance it.

 

[WormsExplorer]

I have a feeling this happened to mine after going on the trail this weekend. When I was on my way out No Vibrations but on the way back home she would vibrate when I would be costing or slowing down. When accelerating no vibration.

 

[RangerX]

I had a rock contact my driveshaft one time while off-road, and it it dented it enough o be unbalanced at speed. Drove hundreds of miles home on the freeway, then got it rebalanced at a driveline shop.
You might take a close look at yours on all sides, see if there’s a dent or scrape or one of the balance weight got ripped off.

 

[WormsExplorer]

I had a rock contact my driveshaft one time while off-road, and it it dented it enough o be unbalanced at speed. Drove hundreds of miles home on the freeway, then got it rebalanced at a driveline shop.
You might take a close look at yours on all sides, see if there’s a dent or scrape or one of the balance weight got ripped off.

Will have to check into that tomorrow. Thank you sir.