Old thread already but I did want to post the fact that the "hood stiffening rods" are indeed listed in the Henry J parts book. They were introduced on the '52 models and they are listed in the 1952-53 Henry J Parts Supplement, under section 18.100 - Hood, as "Brace, Front." It says the K523, K524 (B series, which is Corsair/Corsair Deluxe and not Vagabond), K533 and K534 cars each have two and they are part number 213460. My '52 Vagabond did not have them but the guy I got the car from had lots of '53 parts among it. Lucky for me, in the trunk was a set of these hood braces. I've always had a '53 which had them standard, and when I got the Vagabond it was easy to see why they are needed! The hood wobbles like crazy without them and I think that's the reason why you see so many '51s with cracked/missing corners on hood mouldings. I installed them right away.
They are easy to make if need be, 1/4" round stock or even a stiff, flat metal strip would work. They are fairly concealed when installed. If we ever get a Spring here, and I can get my cars out, I'll take pictures and post.