http://www.rccaraction.com/blog/2011...ule-amendment/
http://www.roarracing.com/?p=1438
Rule 8.2.3
All chassis in all electric classes (except those specifically noted) MUST accept batteries up to the maximum dimensions allowed for its application. The legality of a chassis will be determined as presented to technical inspection. Chassis that require a configuration change, and/or a modification to fit a battery of maximum dimensions will not be considered legal, and the racer will be disqualified. Foam blocks/spacers are permitted to secure any size battery in its position, but the aforementioned spacers may never be attached to the chassis. The only exception is 1/8 off-road where it’s common to use two battery packs to achieve the maximum 4S configuration, or to use a single 4S battery, which has a different specification. Only under these circumstances will the fitting of either configuration be considered legal, but the production chassis must still conform to batteries of the maximum allowable dimensions.