TX has released a official nice looking guide to end the confusion in the 4 different Corona Motherboards of the 360 Slim. This guide will tell you what you'll need based on what NAND chip you have installed on your Mobo. It lists if a JRunner/NAND-X is needed or the SD NAND method, POST_OUT fix board needed or not. I've also included a link to the picture in my 360 hacking thread. Source: HB-Connection.