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@
4x4runner2002
said, the joint just popped out. We are assuming though it's the inner joint because that's the one that slides and can pop out. That inner joint is a tripod joint with three rollers that fit inside the housing. The rollers most likely pulled out and they are no longer aligned with the housing they slide in and out of. Grab the inner housing with one hand while rotating the shaft and pushing in towards the differential with the other hand. Once the rollers line up, it will slide back in place and you will be good to go.