Mafac Racers have the clamp at one end so you can adjust the length but 451s have a fixed soldered barrel at each end. I had a quick look at the usual places I find bits for my Mafac Racers at and have not found any. Tried Compass Cycles as the do replacement parts and remanufacture the Racer brakes but they only have the adjustable cables.
Best bet would be to try and find the barrels or a very similar one and then solder up some new cables. Just use some high silver content stick not the coil of home electric type stuff.
I know what you mean Peter, a cut down Shimano gear cable has just the right end for the Mafac Racer straddle. Good way to recycle old gear cable and also a lot cheaper
When you click on links to various merchants on this site and make a purchase, this can result in this site earning a commission. Affiliate programs and affiliations include, but are not limited to, the eBay Partner Network.