Can an skyline rb20 harness be used on a skyline rb25?

I've seen people remove RB20's from their Skylines in Japan, and throw in RB25's. They had to modify the harness(splicing, etc...) I was involved in the installation of the engines, but I did not modify the harness. So, you will need access to a wiring diagriam, and persons with experiences modifying RB harnesses.