Here is description of how to do it correctly colour code may vary from year to year but wiring principle is the same for all chevs back to 1955.Wiring colours quoted are for a 78 vet
Remove / cut yellow wire from l/h stop tailight .
Remove/cut dark green wire from r/h stop taillight.
Leave enough length to reconnect new wire onto tailights.
Remove white wire from brake light switch & tape up.
Run new white wire from brake switch to rear of car connect onto wire tails from stop tailite sockets .
Replace single filament sockets on reverse lights with twin filament sockets (HQ-WB holden or commodore sedan rear light) cant remember which ones i used fitted with minimal modification to reverse lites.
Orange globes have offset pins so check the sockets correspond.
Untape holden loom to get plenty of length on wires
Fit globes to sockets & identify wires ie common(neg) , bright filament is blinker , Dull filament is revers lite.Connect sockets to existing wiring lite green is reverse lites (L & R), Yellow is left blinker, Dark green right blinker.
Function check all lights prior to reinstalling lites.
White wire that was removed from brake switch can be used to flash rear lights ie like a modern car if immobilizer or central locking is fitted to car.
Material required HQ - WB rear tailight loom, 2x orange double filament globes
GM pn 9438850 Ac Delco L2057NA ELKO 22860-1
I have a modified wiring diagram which can be emailed if required
