Sweden had the small rear light on K6 too.
We got Sandcasts, K0, K1, K2 until 1975 and K6 from 1976.
I had to order rear fender to K1 to fit the rear lamp.
The rear fender we got is not available anywhere with several oval holes for mudflap.
I caught a NOS K1 rear fender in time while still available a few years ago, total around $300US.
Front fender to late K2 and K6 where sold cheaper ss complete NOS from DSS UK than aftermarket knock offs for ca 4-5 years ago.
I see now that NOS K1 front fender cost more than double than around 3 years ago. DSS UK. (Same as early K2)
I checked the price when I sold a good looking one to a friend.
My K2 build got the new fenders I had bought for my K6.
I sprayed both insides with car body bitumen. Rattle can. Sand and small pebbles will not hammer inside fender.
It might be this product in different rattle can than I bought 2018
https://www.biltema.se/en-se/car-care/car-maintenance/corrosion-inhibitors/sill-protection-spray-500-ml-black-2000047132