[Fulltiming]

You will probably need about 550-750 lb-ft of torque to break them loose. You may be able to do it with a heavy duty 1/2" air impact wrench but it would be close to its max if not exceeding its limits. 1/2" air impact guns claim anywhere from 350 (Husky, Kobalt) to 750 (Ingersol TiMax model) lb-ft of reverse torque but those with the higher torque require around 5-6 cfm @ 90 psi. That is above the 4.8 cfm max output of my DeWalt 4.5 gallon, 15 amp, 200 psi air compressor. The engine driven air compressor would likely produce at least 7.5 cfm @90 psi.