It can be confusing. And on top of that, changing rear gears isn't something that is easily done unless you have a quick change rear. In your case changing from 3.08 to 3.36 would not make a real noticeable difference. Also, the rear you would want behind an automatic would probably not be the gear you would want behind your 4-speed. I would get the tranny issue finalized before doing anything with the rear.