Andrew, I have registrated these more deep groved grip ring already in the first pics you have shown. I am a collector who has seen a lot of things, on items itself and on period photographs, so personally I am not the pure "textbook" type. ALCOSO diplo/gov daggers normally (at least what I remember from the few disambled in my very early days) have all parts numbered (against EICKHORN which have mostly only certain parts numbered). So in this case we would have to examine this ferrule very carefully if there is any mark (there are several possibilities of marks not necessarily numbers) corresponding with the other internal numbers "71". Generally this certain deep grooved ferrule matches perfekt in size and patination and it would need inspection if also the fit is perfect as it should be (unfortunately this is not an easy thing with a once disambled diplo/gov).
I have checked all my personal daggers and my reference photographs of ALCOSO diplo/govs and I have to admit that I found only those with the small shallow grooves.
As the dagger seems to be in very well overall condition it is hard for me to believe that somebody has switched this ferrule. I also cannot detect any other dubious part. all the parts semm to be totally and typically period. On the other hand I am not aware of the fact that EICKHORN and ALCOSO did change parts during the period.
There are miracles we will never solve for sure.
Regards,

wotan, gd.c-b#105

"Never look for sqare eggs" as a late owner of an original FHH-dagger used to say.