Can a rear differential slip like a transmission??

Im pretty sure im losing second gear, but when it first started going out, it was strong when I was going straight, but around corners it would start to slip if i got on it. I would think a transmission would slip no matter what. But since the tires are moving at slightly different speeds while turning, it would make sense it was the rear differential is slipping.

Thanks

 

Actually if it happens only when turning corners I would bet on low fluid level and there is no such thing as a little low with the 60e .