I have a 2000 dodge 1500 4x4 it's got 5" suspension lift and 3" body I'm running 37x12.5r20 I'm having problems with the hub assembly keeps breaking I've had to change driver side 5 times and passenger side 3 times any ideas on what could cause this....ps out of alignment pretty bad

 

Your solution is simple. Your tires. Also anything but Timken is weaker as Timken is stock

 

Yep. Either stop running 37s (35s are max on Dana 44) or swap in Dana 60s. Also check the torque spec.

 

That or get a kit and change them to the old style stub shaft and tapered bearings. It's around $1200 though, I think.

 

its not the tires (not completely) or size of the tires, i run 37's as well and run my truck hard off road (jumping and hitting whoops at speed). my hubs hold up just fine. Problem is probably the offset/backspacing of your wheels. Too little backspacing (making the wheels stick out further then stock) is much harder on the hubs (or unit bearings) then larger tires. Google scrub radius to learn what is most likely killing your wheel bearings.
Like mentioned above, use only Timken bearings. Or if you can find them SKF makes good bearing too.

 

Not torquing the axle nuts properly will lead to premature failure as well.