y piece clamp fixing nut

[hodgo]

hi guys,

need to get an additional y piece clamp fixing nut. not entirely sure of the size / spec - i bought a pack of m6 nyloc's but they feel tighter than the other original nut which looks like this...http://www.racetechdirect.co.uk/tvr-car-parts-detail.asp?CATID=3&SUBCATID=21&PROID=615

any help appreciated!