Look at the rectangular part just inboard of the axle gear teeth- - - - -I believe it's part of a multi-disc clutch pack like one I ran in a dirt track race car back in the 1970's. That one also had a fully enclosed carrier where the spider gears were not visible. Try inserting an axle shaft into one of the side gears and see if it can be turned without also rotating the ring gear- - - - -if it's a "locker" it will take a considerable amount of effort to make the axle turn with the ring and pinion blocked in some way, like holding the pinion flange in a vise. On an "open" rear end, the axle gear will turn easily.
Jerry

"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln
Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway
Love your enemies and drive 'em nuts!