I want to keep the stock radio but upgrade to a new amp I have searched for an adapter to convert radio to RCA but I can’t seem to find an answer does anybody have a link.

 

You have two options:
1. Buy a device called a line out converter. Information on line out converter
2. Buy an amp that accepts line-level inputs.

For either option I recommend that you talk to a product advisor at Crutchfield or a similar company. They can discuss the pros and cons of each approach. If I were doing this, I would prefer the option that minimizes the need to cut off wiring connectors or otherwise disturb any OEM wiring.

Good luck with your project.