Don't know of any companies yet............Bob Drake has plans to make a complete '40 Ford coupe in steel.........one piece at a time. He's a ways off.

'40 and '41 Fords have very different fenders from one another unless you're talking light truck based vehicles.

All of these are "relatively" available. Ebay for instance has '40 Ford fenders almost all the time, the Chev less so. The Fords go for ~$200......of course condition and competition can change that dramatically from time to time. The right rear is the toughest to find in good shape.