??Rear & front diff oil change

[flyer1]

Does anyone know how much less oil you need to replace when you do a gear change. Is it always to the fill plug?
I have an 06 rubi and found a tag on the diff that states 60 oz oil + 4 oz limited slip. I went from 4;11 to 4;88 gears. I can only get about 40 oz in it before I get overflow. Any suggestions? My front has a Solid diff cover with the fill plug up about 2" higher than the stock cover. The tag on it states 45oz + 4 limited slip oil. ?? help Is there a rule of thump on gears??

[SilverXJ]

I just fill to the bottom of the fill hole.