rear end locking up..?? or somthin

has anyones rear end ever locked up, almost like it froze or somthin. the last few times ive moved my truck, it acted like the rear end was frozen when i tried to take off. i could feel and hear the clutch grabbing, and the motor wind down and then the rear end made a poping sound and broke loose. this has happend the last 3 or 4 times i moved it. the one day i took it to get exhaust work and it did it when i left but i didnt hear any noises on the way. then it did it again when i went to take her home. im hoping its not in my tranny but it sounds like its in the rear. any info would be great. id hate to swap my rear end and it end up being my tranni.

Do you know if the rear brakes are OK. Any chance this was happening after you set and then released the parking brake?

i thought about maybe my ebrake cable freezing up or getting hung up somewhere but i can deffinetly feel and hear somthing break free when taking off. its like the wheels are stuck at first. but it only does it the very first time i put it in gear and start letting off the clutch. the other day it did it when i was leaving to get exhaust work done and it didnt do it at any stop lights or anywhere else while driving. then i took it to work for the rest of the day and when i left work it did it after sitting for a few hours. so it seems that it only happens after sitting for awhile.

Sitting for a while with the e-brake on? Or off?

does it with brake on or off, just had my dad confirm it. i left the brake off last night cause i was gonna test it today, but he wanted to haul some wood while im here at work so he tested it for me.

and i will add that it does it in reverse and first gear.

What I would do:

Let it sit so that it happens again. Jack up the rear end so the wheels are off the ground, put into neutral, handbrake off. Spin the rear tires by hand, see if they spin or one is locked.

ite ill give it a whirl tonight when i get home and if its locked in nuetral ill disconnect the driveshaft and determine for sure if its the rear end. im pretty sure it is tho. thanx cusser!

If you have a "clunk" when you let off the gas, then hit the gas again, I would say you have a broken differential cross pin.
If that's the case, you will need a whole center section replacement, because your differential is worn out where the pin sits, and the spider gears will have funny wear on them too.
When my pin broke, the rear locked up while I was driving less than 25 mph, and I twisted my drive shaft in two.

theres deffinetly a clunk and its when im letting off the clutch. hell i give it more gas and hope it pops out without blowin gears all over dads driveway. lol but yea its kinda between pumps of the gas pedal while taking off like u said. but if/when it gets worse ill just throw my other rear end in if i gotta. thanks for the tips guys.