Good luck! Which section of the hinges do you need, the plate that attaches to the hinge post or the plate that welds into the door itself? I only have two of the plates that attach to the hinge post.
The rear hinges are not reproduced and usually not available separately. You'd need to find a decent set of doors. For the Panel trucks, the two toughest items to find are the original front bucket seats and a good set of rear doors. Both are made of "unobtainium" and command big $$ whenever they're found in decent shape.
Most rear doors rust out in the hinge areas and crack in the belt line. The doghouse also cracks above the front doors towards the back edge.
How do I know? Because I own two Ford Panel trucks. One is a 1951 and the other is a 1952. Both are all original and 99.9% stock.
My 51 had a rusted out upper hinge in the right rear door. I had to buy another Panel truck (1948) just to get one good rear door. Sometime last year, I got lucky and found the left rear door for $75 in SoCal. Had my brother pick it up next day. I suggest scouring the local Craigslist, Ford Barn and Ford Truck Enthusiasts site for the parts. Someone might have some crappy Panel doors with decent hinges.
I'm heavy into parting out 1948-1952 Ford trucks. If you need a part, let me know. I likely have it or can get it. Also, if you have any questions, let me know. I eat, breathe and sleep these trucks.
Is yours a standard cab or a 5 Star Extra (Deluxe) cab?
Here are my Panels. First, the 1951.
And, the 1952.
Here are some helpful websites to check out and join. I especially recommend FTE. There are a bunch of friendly, knowledgable and great guys on that site, including me.
FTE - 1948-1960 Ford truck forum Ford Barn