S/N 39-280 is a P-40. The P-40C had shackles for an external fuel tank. This lot carried S/Ns 39-156-289; 40-292-357.
The first deliveries of P-40s (no letter assigned) lacked self-sealing fuel tanks and were used only for Stateside training. This aircraft is certainly assigned to a training unit (RTU).
My regards,
Widewing