Jim, yes the shafts are clearly marked for proper assembly to each other.
Now, if you used the front half of yours, and another back half, I don't know if the two would maintain proper balance even if the respective factory marks were aligned (probably not). But, if you buy a rebuilt unit, they will provide both halves, properly balanced and marked for mating.
Do a search herein, several shops recommended. As Doc said, some use greasable joints, some don't. But greasing is a really big job when you have to remove the exhaust to get to the joint. But I bet any of the rebuilts, even totally neglected, would outlast the rest of the car at this point.

DG