New guy, odd question

[michaelssmith21]

I recently bought a 72 Suburban C10, and while going through everything seeing what works and doesn't, I can't seem to find the purpose of the pull knob next to the heater control. Its on the right side, opposite of the ignition switch. The car doesn't have A/C, power steering, power brakes, or a manual choke. I've tried pulling, pushing back in the knob, and nothing seems to change. Its probably something obvious, but I can't seem to figure it out. It took me a while to figure out the reverse light switch on the floor, mostly because mine doesn't work.
Below is some pics of the current suburban, and what I hope to eventually turn her into. Thanks for the help.
Mike