its for class a2 hillclimb and thats all it says about the cage
and ive got to put rear seats back in

thanks for the help

thats the full thing
h) INTERIOR FIXTURES & FITTINGS.
Removal of seats and interior trim (with the exception of carpets/floor mats), is prohibited.
Front seats may be replaced by fully trimmed "competition" seats. Rear seats must remain as original and be fitted.
Windscreen may be replaced by one constructed of laminated glass. The construction material of all other windows may not be changed and the opening mechanism, as specified by the manufacturer, must remain fitted and be operable.
Internal safety roll-over bar(s) may be fitted, but no suspension loads may be fed into them.