More than likely the seal was leaking prior to this but if removing the drive shaft to replace the u joints the seal was compromised.
Basically the slip yoke when removed can damage the seal.
So to replace it we need to just remove the drive shaft again and replace the seal.
I attached the process below on how to do this.
Please run through this and let us know if you have other questions. Thanks
Images (Click to enlarge)
Sunday, September 5th, 2021 AT 8:12 PM