I dont know. I just took one of the 10mm with the undersized heads and used the thread checker at the ACE or True Value.

 

I thought these crossmembers we're an addition to the D2 that didn't exist on the D1? Are they different frames all together? I can't recall where but I remember reading that they were added for rigidity but done so in a way that didn't make much structural sense (small bolts, lower profile to hang up on rocks, etc).

 

IMHO. The cross-member is NOT structural. It's there to protect the integrity of the catalyst body. It may offer "some" support but it's not a crucial element. Repeated: The bolt size/diameter/grade are a dead give away.

This is my hypothesis and it's is not intended to sway the opinions of others. Do your own research.