Aznpersausion

Since you have a 2003, you already have the larger r50 rotors. There are no other brakes (rotors/drums) that will swap right in unless you do a rear disc conversion. That involves parts from an older wd21 pathfinder. It's not easy work and the benefits probably aren't worth it.

I just saw you previously posted that you upgraded your rear shocks to the more expensive bilsteins for no good reason. You were even looking into OME struts...crazy. That money you could have saved with the 5100s could have been used for a rainy day such as today. My opinion is you need to get smart with your money. With that said, your transmission is almost certainly done. Have you properly checked the fluid level? Here is the FSM: https://www.nicoclub.com/infiniti-service-manuals