drive shaft

[bigd65]

is there a front and rear of the one piece drive shaft. i noticed while i was doing the U joints that one side it had a larger weight than the other side. the larger weight was on the front (tranny side) and the smaller weight was on the rear (differential side) when i put in the new JOINT on the front, i got the JOINT in backwards(the grease mite,zerk whatever you wanna call them hit the yoke and broke off) i got the old grease mite of and removed the yoke and jut reinstalled on the other side. i figure the whole shaft is balanced so it should not make a difference. well as i drive it at highway speeds, i feel a small vibration. now im thinking this is from the tires needing reballanced, have not been in 5 years the tire have been on. i dont recall if it was there before. i also think this vibration could be just from lack of play in the new JOINTS that the old ones had.
is there a front and rear of the drive shaft ?
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85 C10 LWB 350/700R4
"THE GHOST"
Jeff Dodson