May need a driveshaft intended for an 8.25 or 44 vehicle, they have a longer pinion on the diff. Pick up a rear driveshaft from an 87-95 donor with a rear 44 or 8.25, any tcase (231 and 242 share the same front to back length for driveshafts), the same transmission and engine as yours has. Or have yours shortened a bit and rebalanced but that'll probably cost $100+.
I'd check your local (CO chapter) classifieds and post a WTB ad if no one has one listed, stock driveshafts generally aren't worth much. If they weren't all smashed up by forklifts at the local you-pull I'd have a choice between half a dozen donors for $20-30 per driveshaft.