can't seem to get rid of dreaded driveline vibration on my 89 300se 41mph to 55mph,is it possible to install driveshaft in reverse order as the half shafts look the same length,the rear half has the u-joint onit as it is right now,i've tried everything,reset center support and tightened slip joint with loaded suspension,moved center support around,vibration speed changes when i move the center support to various positions,it does seem to dissapate as the vehicle warmsup,smooth above 55mph to 70 mph,time to take it to a indy repair shop i guess,must be drive shaft out of balance or bad u-joint,everything is new but no dice,thanks for all the help i received so far.