I don’t know the exact size in kilometers, but just consider hand at six is shorter than hands at 3 and 9 in the zenith forum sure someone can help you faster than the general forum
By the way, this web site will help you a lot with all about A386 https://alphahands.com/vintage-watch-research/zenith-a386-el-primero/
This is a photo of mine. No idea what the measurements are. IfI can help you with anything, without taking my watch apart, let me know!
My guess (it's like a carnival!) is 5.0mm for the second and minute, and 4.2mm for the hour, based on images. Comparison here: https://alphahands.com/faq/zenith-a386-sub-register-hands/