Heavy equipment mechanics

[The Luke]

Anybody in here a heavy equipment mechanic? Dads got a d5 dozer. Bronco72 has helped get me pointed in the right direction of fixing it. But I'd like to know what this is called. This is on the rear axle. Looks like a cast cap is missing that sandwiches the rear axle and goes to an arm under the dozer that's makes a 90 over to the rollers on the track. Passenger side is intact.
I don't claim to know anything about this. So if everything I said is wrong, please educate me.

 

[The Luke]

One pic is complete passenger side arm.
one pic is with the missing top cap and 4 bolts
One pic is on the side with the missing cap showing that it goes to the back of the tracks/rollers

 

[RustyC]

Cap assembly for the roller frame to chassis mount. There is no driver or passenger on equipment only left or right as if you are setting in the seat.
I think you are needing a part #1S5315 that is using a 63J ser# prefix.

 

[The Luke]

Cap assembly for the roller frame to chassis mount. There is no river or passenger on equipment only left or right as if you are setting in the seat.
I think you are needing a part #1S5315 that is using a 63J ser# prefix.

Yea I figured If I said left or right someone would say "is that my left or your left".

that's exactly what I needed. Thank you