i need a indestructable rear diff, please help

[blueb8llz]

hey george16, thats funny how you said that, i was just looking at those nova cups on ebay. are these the ones your talking bout

http://cgi.ebay.com/DIFF-CUP-S-Maxx-Aluminum-Traxxas-2-5-3-3-Differential_W0QQitemZ330271679759QQcmdZViewItem?h ash=item330271679759&_trkparms=72%3A1205|39%3A1|66%3A2|65%3A12|240%3A13 18&_trksid=p3286.c0.m14
but it says pick the 3mm hole mounts only if i have modified gears. which i dont, im using the stock traxxas gears. will it still fit or no. if not, should i still get this with the 2mm screw holes? i think as long as i get this case, the screws shouldnt matter tooo much would it.
one last thing, should i purchase a AL casing? i think thats also just as important, cus that flexes and causes the ring and pinion gear teeth to break.
heres one i found for cheap
http://cgi.ebay.com/T-MAXX-2-5-3-3-E...QQcmdZViewItem