replacing turn signal on L2900

[Fastball]

Hi all....
Just finished smashing my round rear amber flashing/turn light assembly on a low hanging branch. Bought a new 4 inch amber light assembly, figuring it would be a matter of cutting and splicing a couple of wires. But no.
The original has only one wire leading to the bulb holder and the new light have two wires. I'm assuming the other wire for the original is tied up in the wiring harness someplace. Can I buy an assembly with a bulb base with only ONE wiring coming to it?

 

[Gordon Gould]

Is it mounted on a metal fender and the light assembly grounded thru the metal frame ?? If so just connect the ground wire of the new lamp to the under side of the fender with a small lug and machine screw/nut. Remove some paint under the lug of course.

gg