There website sucks- What studs for a DART big M block with AFR aluminum 357 CNC heads.

12 point nuts 235-4303 or 12 point nuts and undercut studs 235-4703 . Give them a call to confirm 800-826-3045 .

Thanks - WHY would you want undercut studs???

The undercut portion is a smaller diameter than the thread's root diameter. By doing this they move the point of highest stress out of the bolt's jagged threads and onto its round and smooth shank. Now it's much easier to deliver a more even preload force and the weaker threaded area operates at a lower total stress.

Figured that was the reason. just wasn't sure. So why wouldn't you use the UC studs?
I am in the process of ordering all of the parts for my new 598 BBC. So regular or UC???