Can you post a photo of the differential with the rear cover removed? That looks like pieces of one of the spider gears. To change the axle seals, you started with removing the pin with the 5/16" hex head. That allowed you to slide out the 1"-diameter steel pin. That pin goes through the two spider gears. You can make those gears rotate by rotating one wheel. The other wheel will rotate the other way if the transmission is in "park". I suspect you'll see the missing section on one of those gears.
This entire assembly with the four small gears is what allows one wheel to rotate faster than the other one when going around a corner. It will still work with one missing gear, but strength will be compromised. Also, if it causes a second gear to bind and crack or break apart, you'll be sitting on the side of the road. All of the driving power will go to the side that is spinning freely without turning that axle shaft.
Given the odd shape of the teeth, this might also be part of a locking differential. If you have that option, you'll see either a set of small clutch plates, or an S-shaped band of stiff metal between the ends of the axle shafts. Those won't stop the truck from moving, but I'd be very worried about chunks getting caught up and damaging other parts.
These smaller axle and spider gears aren't critical as far as gear noise because they rotate very slowly, and at times, not at all. I'd be tempted to find used ones at a pick-your-own-parts salvage yard, or to get them from an axle that's being tossed out for scrap metal. No need to worry about tooth contact patterns like we do with the ring and pinion gears.
Wednesday, January 1st, 2025 AT 2:16 PM
