1989 C3500 trucks were fitted with either a 6.2-liter engine or a 7.4-liter engine. The 6.2-liter engine produced 143 horsepower and 257 ft-lbs. of torque. The 7.4-liter engine offered 230 horsepower and 385 ft-lbs. of torque.
Regular cab C3500s had a wheelbase of 131.50 inches. The extended cab C3500s were designed with a 155.50-inch wheelbase. Regular cab C3500s were 212.90 inches long, while the extended cabs were 236.90 inches long. All 1989 Chevy C3500s were 76.4 inches wide.
All of Chevy's 1989 C3500 trucks were three-speed, automatic transmission vehicles featuring 25-gallon fuel tanks. The bore and stroke was 3.98 x 3.82 inches on the 6.2-liter engine, and 4.25 x 4.00 inches on the 7.4-liter engine.