Drive shaft installation
 

I am buying a good, used rear drive shaft for my 1996 4runner (long story). Anyway, do I have to worry about it being out of balance? In the past when I have replaced U-joints etc., I have always marked things so it went back on the way it came off. But, obviously, with a used one from another vehicle I have no way of knowing. Is it trial and error? Do I put it on, see if it vibrates, then take it off and rotate it? Any input would be great.
Thanks, Jeff