I decided to save some money and make a barrel nut thing for the straddle cable as I couldn't find any double nipple cables the right length.
It's made from stainless steel, I used a piece of 12mm threaded studding.
I polished the old rusty straddle cable and it came out very well unfortunately right at the end it got caught on the polisher and hit me very hard in the stomach at around 70mph. When I recovered I found the straddle with a broken nipple on the end. So a waste of time really!
The barrel nipple I made has a grub screw at each end, one end is fixed in place just so you can hold it with an Allen key while tightening the other grub screw.