02 F250 broken exhaust bolts

Have a f 250 that has got an exhaust leak, In looking at it I see the bolts that hold the manifold on to the head have rotted away, Does anyone know how to remove the bolts, There sticking out so once manifold is off I was going to weld nuts onto the broken bolts, But with the heads being allumimun, no heat rite???

You might try pulling em out with pliers first, sometimes those things will turn right out. If that doesn't work, a welded nut would do the trick. You shouldn't need to do any sustained welding so heat shouldn't be an issue. Besides, the manifold gets pretty hot anyway so I doubt a bit of welding heat would do any damage.