http://scca.cdn.racersites.com/prod/assets/2013 Solo Rules Book updated 5-1.pdf
Page 82 Section 14.2
H. Longitudinal (fore-aft) subframe connectors (“SFCs”) are permitted
with the following restrictions:
1. They must only connect previously unconnected boxed frame rails
on unibody vehicles.
2. Each SFC must attach at no more than 3 points on the unibody
(e.g., front, rear, and 1 point in between such as a seat mount
brace or rocker box brace).
3. SFCs must be bolted in place and not welded.
4. No cutting of OE subframes or floorpan stampings is permitted.
Drilling is permitted for mounting bolts only.
5. No cross-car/lateral/triangulated connections directly between the
driver’s side and passenger’s side SFCs are permitted. Connections to OE components such as tunnel braces or closure panels
via bolts are allowed and count as the third point of attachment.
No alteration to the OE components is permitted.
6. SFCs may not be used to attach other components (including but
not limited to torque arm front mounts or driveshaft loops) and
may serve no other purpose.