* Wheelbase: Longer wheelbases generally allowed for higher GVWRs.
* Axle ratios: Heavier-duty axles supported higher weights.
* Engine: More powerful engines often meant a higher GVWR.
* Cab and body style: A heavier cab and body would reduce the payload capacity, and thus the total GVWR might be the same but the payload would be lower.
To find the exact GVWR for a specific 1984 Chevrolet C7000, you'd need to locate the vehicle's manufacturer's data plate (or sticker). This plate is usually located on the driver's side doorjamb, or on the dashboard. The GVWR will be clearly stated on this plate.