Beech 99 Airliner was a twin-piston airplane with a with three-blade constant-speed fully-feathering reversible-pitch props. It carried a flight crew of two, and seating for up to 15 passengers.
Douglas DC-3 had Twin Wasp air-cooled radial piston engines with Hamilton Standard Hydromatic three-blade constant-speed feathering propellers. With a flight crew of two it had seating for up to 32 passengers, but TTA was generous and fitted only 21 seats in their planes.
Convair 240 sported two Pratt & Whitney R-2800s, and could carry 40 passengers in a pressurized cabin. It had a range of 1200 nautical miles and a cruising speed of 240 knots.
Convair 600 was typically characterized as simply a turboprop conversion of the Convair 240 using the Rolls-Royce Dart turboprop . This enabled the aircraft to reach a maximum cruising speed of 297 knots and a range close to 2000 nautical miles.
McDonnell Douglas DC-9 was the first and only jet operated by the airline. It had a maximum cruising speed of 490 knots and could seat 139 passengers, but often was configured with 75 seats in a typical mixed-class operations.
Information for this page is mostly from Endres (2001). Other sources include wikipedia.