Here are some Zastava M98 examples that are not full stock, FWIW. They do not all have hinged magazine floorplates; much like a motor vehicle, there were several levels of options per my colleague who now lives in Croatia, and grew up in that same geographica area when it was part of a nation named Yugoslavia, that no longer exists. Plus individual owners can have used a gunsmith to make modifications as per that owner's tastes.
https://www.gunbroker.com/item/843709559
https://www.gunbroker.com/item/845886601
https://www.gunbroker.com/item/844132217
Prior to the M48, Yugoslavia manufactured the M24 bolt action rifle for military use, in 8X57mm. The M24 had a straight bolt handle as one quick identifying clue. Here's an example.
https://www.gunbroker.com/item/848302875
Some of these were upgraded to M24/47, after WWII but prior to the wars involved with disintegration of Yugoslavia as a nation. Here are a few examples.
https://www.gunbroker.com/item/847351373
https://www.gunbroker.com/item/847910112
https://www.gunbroker.com/item/847914827
Some Yugoslavia M48 military rifles manufactured for military export were designated M48BO, with no national crests of Yugoslavia nor of whatever nation these rifles were exported to for military use. Here's an example.
https://www.gunbroker.com/item/847717146
None of this info is secret to any degree that I've found FWIW.
Zastava also offered a military-style-appearance M63 with 17.5 inch barrel that Mitchell's Mausers dubbed "Tankers Model" solely for civilian market and solely for export in .243 Winchester, .270 Winchester, .308 Winchester, .30-06 Springfield, and 8X57mm. Note the same action is used whether a member of the .308 Winchester cartridge family and cartridge case size, 8X57mm, or .30-06 Springfield family and cartridge case size. There is no "short action" version, same as the Zastava M70, Interarms Mark X, and Whitworth bolt action rifles. The Zastava M63 was never used by any military force, and was manufactured exclusively for civilian export market via Mitchell's Mausers.
https://www.tactical-life.com/firearms/tank-tough-m63/
The thumb cutout on the M63 is visible in a photo here. Keep in mind the M63 was solely manufactured solely for civilian use, and for export solely through Mitchell's Mausers.
https://forums.gunsandammo.com/discussion/37887/used-rack-strikes-again
Here's a M63 currently offered for sale.
https://www.armslist.com/posts/9868918/evansville-indiana-rifles-for-sale--yugo-m63-mauser-8mm
The M63 design most likely used the M1924CK Yugoslavian "Chetnik Mauser" for a starting point. The M1924CK was not manufactured for use by military armored vehicle crews nor civilian sporting use. However there no specific documentation showing a link between the M63 and the M1924CK to my knowledge.
https://simpsonltd.com/yugoslavian-24ck-chetnik-mauser-carbine/
So to sum up a rather important set of bullet points:
1. The Zastava M98 rifle was never manufactured for military use. The Zastava M98 was manufactured solely for civilian use, alongside the M70 bolt action rifle.
2. The Zastava M98 bolt action rifle was chambered exclusively in 8X57mm as this rifle used the same intermediate action as the M48 military rifle. There are variations of features in Zastava M98 rifles. As a side note, if one wants to change caliber of a Zastava M98 bolt action rifle the "X57mm" part should be taken into account for magazine box size. Calibers like 6.5X57mm, 7X57mm, 9X57mm, 9.3X57mm come to my mind.
3. The Zastava M63 has a thumb cutout in the receiver. The M63 was manufactured solely for civilian use, and solely for export through Mitchell's Mausers.
4. The M63 was manufactured in multiple calibers never used by any military (.243 Winchester, .270 Winchester) as well as several calibers that have been used by military forces .308 Winchester, .30-06 Springfield, & 8X57mm).
5. The Zastava M98 bolt action rifle is in no way a military design & issued Gewehr 98, KAR98, VZ24, etc. rifle.
5. None of this information is in any way secret, as demonstrated by multiple hyperlinks.
Before I make a purchase, I like to spend the effort to make as well-informed and as little misinformed decision to my level of satisfaction. Some folks extrapolate a whole lot of stuff on their own instead of seeking additional factual information. I have done my best to answer the OP's question using external links as easy access factual material. The pics in the OP's initial post certainly resemble the three hyperlinked .308 Winchester caliber Zastava M98 bolt action rifles, the first 3 hyperlinks in this post.
To each his own.