Technically the orientation doesn't matter assuming the drive shaft was balanced by itself and the yoke was balanced separately.
If they were balanced together then maintain the orientation.
In the future if you want to maintain orientation use a punch and put a dimple on the mating sides.
At this point it doesn't really matter unless you get a vibration.
As for the narrow end, post a photo.
If it's a stock 67 dart style with the isolator in the shaft the tapered end goes forward and the isolator end goes to the back.
If it was a cut down shaft then I don't see any benefit to it being oriented either way. I would put it taper back as it's the most visable.
There COULD be clearance issues that the taper might be better on one end vs the other.
Post a photo of your shaft.
Also, which way does the narrow end of the driveshaft face? Thanks in advance!
