Is it the sagem coil pack? Likely to be a double-ended coil pack. ie each spark plug fires twice per revolution (ie 1&3 fire simultaneously, 2&4 fire simultaneously). Normally coil pack HT connectors are marked 1-3 4-2, check sides of coil pack for markings. Each pair of HT ouputs are close to each transformer (each bulging lump in coil pack), so there are theoretically only two possible spark plug combinations.