Driveshaft vibration diagnostics

[Modest_Man]

Had the bushing redone at a pretty good shop here locally about a year ago but hadn't driven the truck any distance until recently. Now when I go over railroad tracks or hit a pot hole at 35-40 the drive shaft vibrates like crazy for 5-10 seconds and then be okay again. It happened for the first time about 30 minutes into a 45 minute drive and then happened several more times over the drive. Not sure if the road was just crappier or if prolonged driving exacerbated the issue. It may have happened once at a stop light on acceleration, I don't exactly remember.

So, any more professional opinions as to if it is bad U-joints, the new bushing, or if it just needs to be balanced? I am leaning toward the U-joint, but driveshafts aren't my strong suit. Maybe I installed it 180 degrees out?

Original 1 piece driveshaft, if that matters.