5513 Questions/comments

[obstando]

Hi

Firstly thank you to all the incredibly knowledgeable members here for all of their selfless input that goes into making this such a fantastic resource.
I am seeking some thoughts on my 5513 which I have owned for 3 years - I haven't worn this for a couple of years for some reason but it has been having constant wrist time for the past month so I thought I should really look into it a bit further. The S/No is 1.822M which I believe is 68 although some of the guides say 66. I believe the dial is original and the lume has a pale creamy patina and not the richer colour of some. I believe the insert to be a replacement but I cannot find a good enough resource to help me identify what insert I have.
I would be most grateful for any thoughts and pointers that may help satisfy me as to what is and isn't original and if more images are needed I will post them (although I don't have the facility to open the case at present).

Thank you in advance for your help