I just replaced th 3rd member in the rear differential in my '89 4x4 pickup. Inside the housing there is some type of metal baffle looking piece, it slided back into the axle tubes and locks on tabs on the top and bottom. The one on the drivers side had came loose and I got it to snap back into place....what exactly is this piece ?

Thanks ,
highway

 

the baffle keeps the gear oil, more or less, in the middle of the housing . . . kinda the same way oil pan baffles work, it tries to keep the oil where it needs to be

 

I must have knocked it loose when removing/installin the axle. I't didn't want to fit back in tightly, si i tweaked it a bit and snapped it back in so hopefully all is well