Alright so I ordered timken fc66998 bearings as they said they're the correct part but they're definitely not way too large what's the correct bearing for the rear axle?
A little info on the rear end they are going into please.
If it's an 8.8 or 7.5 then a BCA 5707 is what you want.
Where is the rear wheel bearing located on my 86 Cougar? Is it behind the hub?
Behind the axle.
You have to drain fluid and pull the c-clips in the diff before you can pull the axle. Then you need a tool to remove and press in the new one into the axle tube.
Pretty decent video showing how to replace the rear axle bearing and seal.
https://www.youtube.com/watch?v=VXEqzMVRRso
So I have a lot of rear end noise in my car, it's driving me nuts so I'm having the bearings replaced, is there anything else that would make a lot of roaring noise other than tires?
Let's start another thread to address any issues other than the axle bearings and seals.
Lots of things can make road noise. Anything that moves.