What Steps Should be followed for Upgrading RT

Hello All

I am doing some prelimiary research on the requirements for upgrading to
RT 3.8.5. I had a bunch of custom code implemented into our RT version, I
was wondering if their is a detailed change log between RT 3.6.3 -> 3.8.5 ?
Or an installation guide for upgrades?

I have oracle 9iRC2 in my back end.

Any help is highly appreciable.

Thank & Regards