reverse/back-up dash light

[RR70]

Was wondering where on the firewall of a 70 RR, the single wire on an original reverse/backup dash light passes?? Mine has a grommet on it, looks original, and not messed with. The green wire goes into the "Z" spot on the bulkhead connector but I don't see a hole to go thru. I think it should be about the size of a nickel?
The grommet pushes into the "mystery" hole from the inside because of the position it's on on the wire. Maybe this isn't the correct year of light??
Any help is appreiciated.
Thanx,  Rod