Vibration after front Aussie install.

[Mr Rock]

After installing the Aussie I get a vibration around 55. It's the front drive shaft as I took it out and can do 75 with no vibes. 
I changed out the u-joints but the vibration is still there. There are weights on the driveshaft so i think it's balanced. There appears to be some "slop" in the slip joint. Should there be any sideways movement in the slip joint?

So what are my options?
1. Take out the drive shaft on long trips and install at the trail head. (this is my short term solution)
2. Send out the drive shaft to get balanced. (Only to find out that it's NG)
3. Find a replacement out of a TJ that is already balanced. (What year would I be looking for?)

Thanks for the help!

[gearhead1985B]

get the ds balanced or find a later model ds (95 and newer make sure it is from the fame engine and tranny combo ie 6cyl and a manual) my ds had slight vibes untill it let go @ 80mph made a cool sound and destroyed my down pipe