8.75 Rear Gear Change Question

If you own a Mopar, you have 1) a open rear end or 2) a Sure Grip rear end, end of this part of your question.
Next to change from a 3.23 gear ratio to 3.55 or any other is pretty straight forward.
Now to accomplish the gear change properly so that it holds up to abuse and does not whine, that is a whole different mater.
With no knowledge of doing this, you would be better off to buy a third member from someone like Randy's Rears,Dr. Diff or one of the other reputable vendors.