The engine in the pic is for sale. It's had 2 previous owners...each hoping to complete their project with each not getting around to doing it. It's factory new. It's never been assembled or run. We currently have a free air 503 on my dad's spitfire that I've been flying now for 4 years now. He's had many engines on it, but nothing compared to the 503! I have a 582 Gray Head that needs work done to it and a lot of parts added that I thought about mounting on my spitfire that I just bought last summer, but am leaning towards a 503 for the simplicity of it...no messing with coolant, thermostat, potential seal failure etc.