If you use those modern plastic turn signal lights...I'll never talk to you again!!
To me, thats the worst thing when i see "hardware store" lights for turn signals on old cars. Why not use 32 light buckets, replacing one socket with a duel filament type so you can have brake, turn, and running lights in the same bucket that is period correct for your nice clean old truck. do a google search for light sockets, and the choices will make your head spin. pick the ones you like, make them fit, and throw the plastic in the trash