Dana 30 ujoint and dana 25/27 the same?

Ok, my dana 25/27 driveshaft fits my dana 30. I mean, its two inches too short, but the u-joints visually are identical and the ujoint sits real nice in the yoke. I've never heard of this, am I just finally really lucky?

 

The vast majority of Jeeps up into the later 80's EXCEPT the front driveshaft on Factory V-6 CJ's used the same U-joint. The joint is a Spicer # 153x.