Converting a 4L80E into a slip yoke

So I swapped the drivetrain from a 3500 into my 454ss and didn’t think about the fact that the 4l80 (my truck is a 90 so it had a th400 from factory) has a fixed yoke in the 3500s and I need a slip yoke. So I have two questions, 1. Can I convert my fixed yoke to a slip yoke as my truck is lowered 6 inches in the rear and won’t have much travel at all, or 2. is there a conversion I can get for the trans. I’ve seen some drive shafts that have a slip joint so the shaft itself slips and not the yoke but can’t seem to find anything like that to adapt my driveshaft. Any advice or where I can find answers would be appreciated!