Are there any videos or tutorials for replacing this on a Cougar?
Everything I searched came up trucks.
Cousin also says “Driveshaft needs balancing”
U tube for any year mustang with a 289. The shop manual also explains how to do it.
Pretty easy, overall. I did mine with some sockets and a big ol’ vice. Just be cautious and make sure everything is lined up as you press in the new ones.
If you need details, let us know 
Thanks all!
I wasn’t going to watch it initially because he was doing it on a truck. But now I see it’s pretty simple for all cars… right?
yes, same procedure.