HELP! Shortening my driveshaft

I've found this table in the past http://board.moparts.org/ubbthreads/upload2/4563759-PartNoDriveshafts.pdf Not sure how accurate it is, but it seems like it would work my 67 Dart setup. The only reason I thought it was weird was it listed two different part numbers for the same exact setup for one car (I think a 70 something Duster). The 67 Dart stuff appears to be right though from my measurements.