Grounding Turn Signals

I've found a set of turn signals that I like for my 440B1. Here's the thing: The 440's setup in the rear is for a single lead, that being the hot wire (?). The signals are grounded, apparently, by grounding the entire rear lamp/signal mount (see pic from FSM). Since the mount and the signal housings are both metal, this grounds the entire system (tail light/signals).

Am I reading that correctly? If so, can I use 2-lead turn signals in the rear by 1) Just not connecting the ground lead from the signals and counting on the grounded housing being enough, or by 2) Attaching the ground lead from the signals to the same location in the tail light housing as the main ground wire?

Z1 and KZ use these, these are on auction on ebay right now.
search blinker ground wire.

Color Codes On Most Kawasaki’s (written for 1980’s bikes)

HEADLIGHT
RED with BLACK stripe, High Beam.
RED with YELLOW stripe, Low Beam.
BLACK with YELLOW stripe, the ground circuit.

BRAKE/TAIL LIGHT Can be an # 1157 dual filament bulb
RED, Running or Tail Light.
BLUE,(sometimes with a Red stripe) Brake Light Circuit.
BLACK with YELLOW stripe, the ground circuit.

LEFT FRONT TURN SIGNAL Can be an #1157 dual filament bulb
GREEN, Left front turn signal circuit.
BLUE, Left front running light circuit.
BLACK with YELLOW stripe, the ground circuit.

RIGHT FRONT TURN SIGNAL Can be an # 1157 dual filament bulb
GREY, Right front turn signal circuit.
BLUE, Right front running light circuit.
BLACK with YELLOW stripe, the ground circuit.

LEFT REAR TURN SIGNAL Can be an #1156 single filament bulb
GREEN, Left rear turn signal circuit.
BLACK with YELLOW stripe, the ground circuit.

RIGHT REAR TURN SIGNAL Can be an #1156 single filament bulb
GREY, Right rear turn signal circuit.
BLACK with YELLOW stripe, the ground circuit.