the you are fine...if you wish to upgrade it get the R2 diffs...but i dont think it is worth...better if you get something new then.
As far as parts, the C1 is very strong and as I said it is very difficult to brake parts...i would suggest to leave it and if you break something you buy..otherwise you end up to buy stuff that u dont need!
If you need cen bits ring CEN new zeland, Chris is a top guy. When i had my i use to buy off him every time! Quick and cheap! Unfortunately i just sold all my cen stuff otherwise i could have help u with some spare!