I don't know how you check the ratio on a closed driveline but I amd sure someone here does. I guess that it would involve turning the engine over by hand with one rear wheel off the ground.
The heater is another issue. If it is a round heater with no external intake, it is a recirculating heater. If it is the type that bolts up to the passenger cowl and takes air from the outside, it is a fresh air heater. Both units do fairly well on Ebay but the fresh air unit is more valuable.
