yesterday was the first time I've had my truck in 4x4 and put it to the test going up a long steep hill about 3/4 of the way up it was like the truck stopped pulling for a second rolled back a little "rear wheels spinning" then the front end kicked back in and up the hill i went. I think it might be the lock outs bad but not sure don't want to spend the money and time to replace them and that not be the problem

 

Remember the front axle is an open differential just like the rear. So if one rear wheel is spinning (no traction) and one front tire is spinning with no traction, then you go nowhere and could even slip backwards on a steep incline.
Even if you have limited slip or a locker then you still could see that situation if you have no rear traction and one front tire has no traction. Though the LS or locker would significantly decrease the likelihood of getting stuck.
Put a locker on the front and rear then you have real 4x4 action...

Sometimes hitting the brake on a spinning situation will give some traction back to the stationary tire and you lurch forward.

 

How would I know if I do need new lockouts?