We're running those big lights on both the 53:
http://www.chevygmcofkc.org/Gallery/data/3021/1100_1223-400.jpg
And the 54:
http://www.chevygmcofkc.org/rides/ocoulson/54/images/DCP_0032.jpg
Big and easy to see, I've had several people tell me they are "F*rd" Lights as well as several say they are trailer lights.

When the 53 goes back together it will have 54 round style lights on it with superbright bulbs. Both the orignal correct (for your 51) lights and the round 54 style lights are available from all the vendors.

MONGO


Mongo's Garage
Vintage GM Truck's & Parts
https://mongosgarage.com