It didn't appear to be too short, maybe 1/4"? It was hard to tell because the length can change on them by compressing them and the old one had a tear in the boot and lost grease making it move easier than the other.
I'm guessing more likely it was the set ring itself, or the location of the set ring not fully seating in the diff.
Either way, problem solved.
great to hear you got everything sorted out!!! especially after all the trouble its given you...