I ordered two 80x80x10mm Fans at Amazone because i required another Mainboard/Stepper Cooler for silencing my i3 Mega after replacing the Stepper Driver with TMC2208.
The only available for next day delivery was these: https://www.amazon.de/gp/product/B07DVX3DD4
I had one Fan left, but wasn't able to find a stl for a 80mm psu Fan, so i remixed the PSU Cover of kuehmayer
P.S.: Anything fits mechanicaly, but the fan i bought was to weak to spin.