8 3/4 rear end confusion

Do not hammer on anything that is a slide in fit. If it doesn't go, you are doing something wrong.
Get your Factory Service Manual out guys.
I you don't have one , you shouldn't be doing any service on your car.
Here is the link for a free one.
It will answer 90% of the questions that you will see on these sites about doing different services and repairs.
The dealer mechanics used these manuals at the Dealer.

MyMopar