as for the covers ID, no clue. on the Summit racing I counted 8 such covers.
I have a TA Performance ( I Suport our venders) When you hold a TA in your hand and look at its construction you will have faith it will add strength to the rear. I was a 4X4 nut at one time and I preferred the smaller differential for ground clearance. ring gears and carriers broke often butt adding a girdle extended the life 2 fold. Is it a must for my 11.5 car ? probably not. I put 100+ passes on a OE G80. with 28X9 Hoosier.