7 1/4 Rear End in 69 Barracuda

1970Duster said
Finally, if you opt to upgrade to the either the 8.25 or 8.75 will need to do a few things.
1. You will need new/different leaf springs

Why can someone explain? Also we need a write up and sticky for this type question. Stating this is what you need, why you need it and how to do it. Craig