I have two 336Fm I use the JJC trigger and two receivers off Amazon £27.  

yongnuo 602 triggers with a mono 2.5 to 3.5 jack will work I have used them.

Everyone, thanks for taking the time and energy to answer my question. You've all been brilliant. Whilst many threads on PP become 'difficult (which is why I rarely post) I love that I can post technical questions on PP and there are good people who come together to help. It is much appreciated.