what is the weekest link in 4x4 drivetrain
 

The other night I was doing some wheeling. I have a 89 bronco 4"lift ARB air lockers front and rear 33x12,5 bfgoodrich all terains. I had my rear lockers on and the truck was in 4 wheel drive. I was driving on the side of a creek when I hit a slipery spot and slid into the creek. This is in Houston Tx, so the creek bottom was mud not rocks. Well I had water coming into my cab and I could move forward about 30 ft and backwards about the same but I could not get enough traction to get out. I could not get my front lockers turned on because I didnt have enought space to get them to kick in. All of the suddon I couldn't move at all. After geting it reckered out and got it home. I realized the my front 4x4 was not working. When I climb under the truck and can spin the drive saft to the front and it will turn the dif's to the wheels. When I put it in 4x4 from the cab the transfer case locks in and I can not spin the drive shaft anymore. I have not had it up on a rack or stands and I have not removed the manual locking hubs. What do you guys think I have broke? I am guessing the manual locking hubs. Can one strip out the axels that go into you manual hubs? What would break first? What is the weekest piece to a 4x4 drive train?

I think the weakest parts are the lock out hubs and front axle joints(D44).

From what you describe it sounds like broken/inoperative lock out hubs. It would be odd for both of them to break at the same time though.

It's also fairly easy to snap your outer stub on those axles though the hub usually serves as a "fuse" of sorts and will snap before the stub does. I don't remember if those use an open knuckle design but if so put the t-case in neutral and turn the driveshaft by hand. You want to check if you can see the shaft and u-joint turning properly. If they do then it's a hub.

Yes it would be odd for both to break at the same time. but even if one broke you would get the same result , no 4x4

No, if you have a locker up front one wheel should be spinning on that axle if one hub is broken. If the locker is engaged and neither wheel spins it would have to be both hubs.

broken hub, i had the same problem about 2 years ago.
I used the milemarker replacements, they're really nice.