New Driveshafts to Prevent Vibration?

[TheWhiteElephant]

I lifted my 1973 K20 long bed with a 4" all spring Rough Country lift a few years ago. I have had no driveshaft work at all. Truck is street driven with street tires. There is a noticeable vibration in the higher speeds, maybe 45mph+. Didn't bother me too much at first, but now that I'm driving the truck more, I'd really like to address the issue.

I'd like to get input from those of you who have no vibration with 4"+ lifted trucks, mainly from those of you who have had driveshaft work. What exactly did you do? I'd like to possibly purchase a set of double cardan driveshafts from one of the online vendors, but I want to make sure that I will have as smooth/vibration-free ride as possible before I drop that much money.

Any of you running double cardan driveshafts and noticed a big difference from stock/OEM?

Thanks in advance.