driveline vibration

[77 cc lb]

I am looking into buying an 86 suburban. Took it for a test drive and it had a vibration around 30-40. He said he replaced the center bearing and the all the u-joints. Is it possible he put the driveshafts back together, out of balance? Would that be a constant vibration at all speeds or just around 30-40? Any info would be appreciated. Thanks

[Irish_Alley]

tire/weight problem