At the Singapore Air Force Museum they have a collection of pretty much everything they have flown that has been retired. Singapore used a unique version of Skyhawk two-seaters. The factory-made TA- 4 used a different engine than the Singapore A-4S, so RSAF opted for a dual cockpit version that used a common engine. This reduced costs in maintenance and trainiung, parts etc. The conversions were done locally through a subsidiary of Lockheed. Note the bulged second canopy, it's simple a second standard canopy. Note also the 5 weapon pylons, 30mm cannon and nose, which indicate they have the same upgrades as the A-4S fighters. This aircraft also carries a buddy refuelling pod under the belly.