drive shafts

I have been doing a little reading and looking for a bit of text on the reasons why some trucks came with the types of drive shafts they did.  I know many have opinions and theories but I'm curious as to how the engineers at ford might have explained this. I normally have been using single drive shafts and am now installing a two piece with carrier bearing and just got wondering why two seemingly like designed trucks would have come with either/or.

Mat, in the case of Darth, it is 168" wheelbase, 2WD so the drive shaft would be quite long. My 1977 F150 with a 6cyl and C4 had a 133" wheelbase and a single piece driveshaft.