Changing Fluid on 01 front axle - 181 or 186?

I'm getting ready to pull the front cover off the stock diff in my 2001 XJ and checking hte service manual before hand it calls for 2 different front axles - one is the 181-FBI and the other is the 186-FBI... both take different capacities of fluid. 1.48L and 1.18L respectively. I know pulling the cover and refilling it shouldn't be difficult - I imagine the fill plug is on the back side of the axle somewhere.... so after I drain it and get the front cover back on should I just fill it to the fill plug? That way I know its full? Is there a diff fluid that you guys recommend over the Mopar fluid?

Thanks
Fred

Remove the fill plug first, then remove the cover, drain it, clean it out, put the cover back on, pour in gear oil untill it starts to run out, reinstall filler plug, done.
I usually use brake cleaner and a few rags to clean mine out with..
Oh, leave one top bolt in, backed out but loose, while seperating the cover from the diff, don't want the cover falling into the drain pan and splashing 2 quarts or so of lube all over...

Royal Purple gear oil...i believe its 75w140....

The different axles are probably just HP vs LP D30...I'd imagine the LP takes a bit more fluid....but if you have the 01, you have the LP D30

Fill plug is the plug on your diff cover...

So after I drain it and get it cleaned up - what 'silicone' or rvt should I get to seal the cover back on? Then I fill it up with the fluid until it runs out the hole (that should be very close to the correct amount of fluid)? Sorry for the newbie questions - I have yet to tackle a diff yet and as easy as it sounds i want to have all the stuff I need first before doing the job... so I don't run into trouble with it apart.

Thanks
Fred