Customs exemption for propane vehicle conversion kits requires environmental ministry certificate and is time limited. Amendment inserts serial 145A granting a conditioned customs exemption for kits to convert motor spirit vehicles to propane, and adds Condition 29A requiring an importer to produce at importation a certificate from an officer not below Deputy Secretary in the Ministry of Environment and Forests confirming the kits' use; the exemption is time limited until 31 March 1988.