I collect just ex-yugoslavian,croatian and bosnian grenades so I know the origin of that markings.Also I wrote on Lex's website about them many times.
You have the original yugoslavian made body of M75 grenade,but your fuze is not original yugoslavian which were labborated with that grenade in SFR Yugoslavia.Original yugoslavian made fuze for M75 called UBRM-75(UPALJAČ BOMBE RUČNE M75) doesn't have any markings except printed with black paint four digit black number on the top of the safety lever.
The fuze on your M75 is croatian made copy of UBRM-75,made from 1991 till 1993 for croatian army in the factory Đuro Đaković in the town of Đakovo in Croatia.That kind of fuze was issued with the safety lever without any markings on the top of the lever.Those Đuro Đaković safety levers were also cadmium plated,but you can also find the same Đuro Đaković made fuze with the safety lever gun-metal coated(black) with markings on it's top(RB-M91 and serial and year of production).
The marking on your fuze is factory's simbol ĐĐ,and you can find it on their website:
http://www.duro-dakovic.com/
So you have yugoslavian made body of the grenade and croatian made fuze for M91 grenade,which is Đuro Đaković's made copy of M75 grenade.
That fuze was issued only with M91 grenades,not with original yugoslavian M75 grenades.So probably someone screwed it on the body of M75,but that is hybrid of two different grenades.And it was never used in war on the balkans-just M91 grenade with that fuze was used,and M75 grenade always was laborated with it's original yugoslavian made fuze.