Been trying rid my pickup of its stick vibration and I’ve just gotten new tires, balanced, and alignment and it didn’t help. I’ve narrowed it down to the collar that goes around the front u-joint of the front of the driveshaft, and only reason I’m suspicious of it is that is a siliconed mess from previous owner(also has a lot of play), believe it’s a (slip yoke collar?) but having a hard time finding info on the purpose of this collar. Any help is greatly appreciated.

 

It's a vibration dampener. They're well known for coming off when the rubber fails, and it sounds like yours did at some point, and somebody attempted to fix it. I highly doubt it's in balance now. Unfortunately, the only way to replace it is to replace the slip yoke.