I have an np205 with the long rear output shaft,is there away to swap it out with a shorter output?

Yes that is an easy swap, just find the parts you need, the shaft, the little piece if the housing and the yoke,

what if i have a np205 witha long output withe the slip yoke fitting and the one on my truck has a short fixed yoke are they interchangable?

Yes easy swap, My Chevy 205 had a slip yoke and had a Ford 205 with a fixed yoke was a piece of cake also upgraded to the ford heavy duty 32 spline front output.:D

Is so easy I have even done it still in the truck!