front drive line falls out of u-joint

[spinyata]

Just bought my first tractor.Used 05 Kubota BX2230 with FEL. It was missing the u-joint between the two drive lines for the front wheel drive. I installed a factory u-joint today and the drive worked fine until some rough terrain allowed the front axle to move far enough to allow the drive shaft to slide out of the u-joint. It seems that there's only about .5 inches of contact between the u-joint and the drive line while on level ground. Does this sound like enough? Any ideas?
Thanks. Jerry

 

[Egon]

Check for a pin holding the u-joint and drive line together? It may be missing.

You may have to extend your drive shaft so it does not fall out.

 

[spinyata]

The pin is in the lower u-joint. The upper end of the drive shaft has the longer splines (for some play) but it does also have a spot for a pin. The manual shows a pin only in the lower joint. Should I pin the upper joint?

 

[Egon]

If that drive line moves it can't be pined on both sides. Picture would help.:ashamed::confused2: