Hi replaced one side so far but was looking on here and want to know if ive missed a part. The replacement guide i found mentions keeping one of the old parts as shown in the picture the round part before the nut but the new ones didnt come with one so i just used the nut rather than any of the old bits. Is this correct or should i have used some of thbits off the old one? Hoping i dont have to take it off and redo!

Just to advise anyone doing this the round item is a collar to cover the top of tbe new outer tie rod end not sure its 100% vital but i put both on. Current 2007 TDV8 Vogue Buckingham Blue

Does that collar not clamp down on the outer like a plumbing olive would. I.e. as that nut tightens, it pushes on the collar, and that pushes tigher and tigher on the sloped join of the outer, making it clamp harder on the thread of the inner.

( i would have left it on ) V8 or else ...

Yes it does and your description of how it works is much better than my simply collar one!  Current 2007 TDV8 Vogue Buckingham Blue