I want to correct myself and add that it could be these other karts too:
1708-XXXX various sub model #'s
1720-XXXX various sub model #'s
https://www.bmikarts.com/Carter-Brothers-Go-Kart-Manuals
These karts have frames that more closely match the photos in post #1, the brake and gas pedals match, the live axles are supported by bearing flanges and are "open" and they have factory torque converters like the one in post #1. I think those Carter Brothers parts manuals are just a suggestion of what the karts really look like because they are pretty crude drawings and it's pretty safe to assume some parts manuals are missing from that site.
The 1708 and 1720 karts have dual band brakes operated from one pedal, not sure if the kart in the photos has it or has been altered, but that is pretty nice.
Anyway, I wouldn't hesitate to buy one of these old American-made go karts......as long as the price is right
*We should support BMI Karts and thank them for listing those Carter Brothers manuals.