Later model 2 speeds have an electric motor that moves the shifter instead of a vacuum system. Look at the 2-speed shifter- - - -does it have a switch with wires, or is there a mechanical linkage that moves a vacuum valve? The vacuum-operated rear end will have two vacuum lines and a big round diaphragm on the differential housing.
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!