A couple of additional vendors (all have patch panels as well as full panels):
American Classic Truck Parts has them too. See page 27 of the 1947-54 catalog.
www.americanclassic.com Classic Industries Parts and Accessories.
www.classicindustries.com Truck Shop
www.truckandcarshop.com pp. 44-47 1947-1959 catalog.
I haven't purchased sheet metal, but I've had good service on other parts from all three vendors.
Good luck!
