Martin,
It would seem that the GDC answered that question here,
http://forums.usfirst.org/showthread...ighlight=shock.
"Gas shocks (compressible gas springs) are permitted under Rule <R46>. Models of the shocks that contain small amounts of hydraulic fluid that is used as a lubricant, and which are completely sealed to prevent any escape of the fluid (and therefore not violate Rule <R36>), are acceptable. Hydraulic springs which utilize hydraulic fluid as the major damping fluid, and are therefore not really "pneumatic shocks," are not permitted. "