Without getting changing a stock FF-60 axle what is the max angle yyou should run on a axle of this nature...currently at 10 degree's and need to go up by 10-12 to around 20, is this going to be a problem?

Something like 18 is ok....

FWIW

My RC D60 is at 22*

The steeper it is, the less oil goes to the outer pinion bearing. However, They are designed to stand up to towing a big load at highway speeds, so if you are not running with hubs engaged at high speed, the bearing will probably still live a long life even if pinion is pointed straight up.

Tipping it way up does change the hight of the fill hole though. You may need to put a new fill-hole in the cover. The correct oil level should keep oil in the housing tubes, but below the axle shafts.

He is talking about a FF rear axle so I would guess that there are no hubs to unlock.