AC Milan Kappa Shirts
Mostly, there are a few differences between player issued and replica/fan shirts. One of the difference could be that long sleeved shirts are not sold commercially while short sleeved shirts are. I often read this argument when old 1988/89 or 1989/90 AC Milan shirts (made by Kappa) are sold on eBay or other platforms.
But fact is that – as far as I know and remember – at the time in fan shops there were sold only long sleeved shirts and no short sleeved shirts. Therefore, if you buy a short sleeved of those Kappa shirts, the chance that it is a player issued shirt is already high.
Another detail to watch at seriously is the specific shape and the exact measure of the back number, which wasn’t sold or embossed in shops, but only at the kit stock of AC Milan.
There were and always are many fakes sold around in the internet, often offered as „match worn“ etc., which they simply are not. Once you get aware of the specifications of the real back numbers, you recognize them at once.
In 1989/90 there were a few more differences between player issued and shop replica shirts: One of them is the bigger European Cup logo on the player shirts, which was embroidered below the yellow star.
Further, some long sleeves shirts were produced of a heavier cloth material to meet the cold temperatures in winter.
Last, but not least, some shirts had a different colouring of the collar, which was also never produced for commercial sales.