Just use a 6v power supply with 12V bulbs. If you want to cut the back end out of a sealed beam, use a Dremel tool and a diamond dust cutter bit. Wear a dust mask- - - - -the dust you'll create is very irritating to your lungs!
Jerry

"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln
Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway
Love your enemies and drive 'em nuts!