HELP - In The Middle Of 68RFE to 4r100 Conversion

hello,

I am in the middle of a 68rfe to 4r100 conversion and I have a negative signal coming from the pcs2800 but I need to know which wire on the 68rfe harness needs this ground wire.

Much appreciated on any help you can give

searching i found that on a 2012 truck it is the yellow/green coming from the 68rfe but what about my 6.7 2007.5 can anyone confirm?