Thanks guy's, Ive got the right part number that I quoted to the supplier, whether Ive got the right part is another matter.
I've measured the diameter from the remains of the sheared nipple and its 8mil, give or take a decimal point or so, the problem is the thread pitch, I dont have a set of pitch gauges to check this aspect. If someone has a spare or used nipple that they can measure up and establish exactly what the dimensions are I might simply need to chase out the existing threads, if Ive been sent the wrong part I'll tear them a new one
Hope someone can help on this