go rent an oxy/acet setup. i don't want to tell you again.
don't use an impact gun, just do it by hand using a breaker bar and socket on your snap-on collet tool. keep tension on it while heating and you'll feel it begin to move. heat a bit more and turn it out. if they get hard to turn on the way out, stop and reheat. you should be able to get them all out in less than an hour with the right kind of heat.