nick,
let me clear my comment up for you, the D2 unlike the D1 has a small lip on the front of the axle housing, where a diff guard would attach to. due to this small lip most MFGs went with the 4 bolt clamp style guard. as mentioned above, the bolts come loose and fall out. that is why $G only offers a weld on option...the D1 in comparison has a 1.5" lip, which gives a better area to fasten a guard to, tha caveat is that even with a larger lip, the D1 guards also loosen and fall off.
weld on guards are the best choice. after years of screwing around with clamp style guards, i sewer capped my axles, which is even better than a weld on, but a lot more involved...
get the $G guards and take them to a muffler shop, they will tack the guard on for you for a couple bucks and your done...and best of all, they won't fall off...