Central junction boc in regards to the general electronic module

I have a 2001 mustang with an engine swap. 5.0 ltr from the previous chasis the sn95. Well certain electronic funtions are not working ie the trunk release button. The power door switches the door alarms and the reverse lights on the tilight. After troubleshooting and looking at wire diagrams on both generations I found out that the GEM is supposodly bad on my 01. So I first checked the fuse well thats where the problem comes in the fuse junction box was replaced with the previous generation with the engine and the previous generation does not have a GEM on any models so that got me wondering. Which one is the problem. I cant find any diagrams of the central junction box on either generation. It had me wondering that the central junction box may be the issue but how would I go about changing the box? Any advice on any option would be grateful