First off, the Bronco never came with a V6. It was an inline 6, I6.
Be sure to keep your naming correct, because if you claim to have a V6 and it is true, somebody has been swapping stuff and no telling what you are working with.
So an I6 to V8. Most years had two different GVW packages and part of that was different rear axles. But that option was not tied to the engine choice. Limited slip was also an option, again not tied to the engine choice. They were all 28 spline. Brakes changed with GVW, but not engine.
The only difference in the axles that was related to the engine choice was gearing.
3.50 was standard for the V8.
4.11 was standard for the I6 but was the option on the V8.
4.56 was only available as an optional ratio on the I6
That's it.