The cover really doesn't add overall stranth to the D35 axle, but will protect your housing & gears better then the stamped factory one.
How often to you wheel & what type of wheeling will kindof help detemine the needs of a HD cover.
I rock crawl, trail ride and some mudding and lokoing at getting either the Rock Rings for the covers, or going with the Blue Torch Fab cover.
There was a thread started on this the other day int eh General Thread, heres the link.
Good Diff Guard?