Not to be confused with any of the other Yugoslavian Mauser Rifles, the M-98 is the only one of the Yugo Mauser rifles that originates in Germany. These rifles were used by the Nazis during the occupation of Yugoslavia during WWII, and were captured when Yugoslavia liberated itself in 1944 (the only European country to accomplish this without aid from foreign armies). Another source of WWII German K-98s to Yugoslavia at the time came in the form of war reparations from Germany after the cessation of hostilities.
Following liberation, Yugoslavia's military was understandably critically short of weapons - which was resolved overhauling and remarking captured German rifles, which were similar to those the Yugoslavians had.
Some sellers list the Yugo M-98 as 'German M98k Mausers' - but this is potentially misleading because original markings have been tampered with and as a result do not include the words 'WWII German' in the model name.
The reasons for this involve the arsenal refinishing and remarking of these rifles: original maker's markings and production year have been ground off the receiver and replaced with the Yugoslavian crest.
In some cases serial numbers have added and/or removed, and some Yugo M-98s will bear the 'Preduzece 44' markings of the Zastava arsenal where the rifles were overhauled.
Mausers marked "48" are post-war Yugo-made Yugo 48's on the M98 pattern , since the "48" denoted the year of acceptance - 1948.
I hope this helps you understand what you have.