Locking the rear.....Harder on front axle shafts????

Just curious, if you lock the rearend, will that added traction and push against the front wheels put more pressure on the front shaft? as in enough to break them more? Something ive been thinking about.

You're overthinking. All situations are different, and there is no sure way to know when your shaft goes kapow.. The locker will get you in places you normally couldn't go and in positions you wouldn't normally be in. Its just doing its job. Lock it and carry some spares.