Is my drive shaft too short?

You cannot tell simply by the picture as you have no idea how long that new slip yoke is. The only way to know is to unbolt the rear u joint and push the shaft all the way forward. With the car weight on the rear suspension (not with the differential hanging on the springs.......is it hanging in the pic?) The shaft should slide forward 1", or have 1" to slide back to seat the u joint.