There were several patterns of Kar98s made from 1898 to 1918, but the photos and descriptions that I have are pretty scattered. I sorted out the photos that I have and it seems that there were at least eight models made, mainly by erfurt.
1: Spandau 1898 model, I saw this on the pdf, it seems to be the very first model, perhaps a prototype: http://ycgg.org/wp-content/uploads/2016/08/kar98.pdf
2&3: cavalry and artillery models of Kar98, they look like shortened Gew98 in the patterns of Kar88 and Gew91
4: erfurt 1903 Kar98, which is often called as “Kar98A” but this seems to be an unofficial nomenclature, this model adds a bayonet lug
5: erfurt 1904 Kar98, a further development of the 1903 model “Kar98A”, you can see the difference on the barrel band
6&7: two mysterious transitional models, I saw this pic on K98k forum before but I can’t find the original post now
8: the most commonly known Kar98, often called “Kar98AZ”, renamed “Kar98a” after WWI, and there were also at least four patterns of the “Kar98AZ” but the changes were made on the stock, i.e. hand grooves on the side and disassembly hole on the butt
1: Spandau 1898 model, I saw this on the pdf, it seems to be the very first model, perhaps a prototype: http://ycgg.org/wp-content/uploads/2016/08/kar98.pdf
2&3: cavalry and artillery models of Kar98, they look like shortened Gew98 in the patterns of Kar88 and Gew91
4: erfurt 1903 Kar98, which is often called as “Kar98A” but this seems to be an unofficial nomenclature, this model adds a bayonet lug
5: erfurt 1904 Kar98, a further development of the 1903 model “Kar98A”, you can see the difference on the barrel band
6&7: two mysterious transitional models, I saw this pic on K98k forum before but I can’t find the original post now
8: the most commonly known Kar98, often called “Kar98AZ”, renamed “Kar98a” after WWI, and there were also at least four patterns of the “Kar98AZ” but the changes were made on the stock, i.e. hand grooves on the side and disassembly hole on the butt