A proper retro-ist should know more than me as a 21st C bicycle shop, but I think the fat brake cable, 2mm/6mm iirc, hasn't been available for decades. Most modern brakes won't take the outer.
There might be a repro source though.
If you can see the spiral on the gear outer, it's probably cheap rubbish.
Proper index cable has a very stiff, slow outer spiral, and needs quality cable cutters to cut neatly.
Cheap bikes and bsos often don't have real gear cable.
Out of choice on gear I always use sis-sp51, 5mm stuff takes brass end caps. Smoother, stiffer, stronger.
Many other retailers dont even know it still exists.
