It was this one. https://www.ebay.co....bwIAK:rk:1:pf:0
I think, (as I didn't measure) the hole I was left with in the bulkhead was 1/4", witch is 6.4mm, as there was a slight bit of wiggle room. With the cable end being 8mm and the nut being m6, 10mm spanner size. And I shortened mine by about 5 mm, witch i new I'd have to as the 25mm ones were the shortest I could find.