I just did this about a month ago. You have to grind real deep Into the knuckle horizontally for the cracks to start forming. Don't even waste you time beating on the knuckle till you have a crack all the way around the tube.. Mine were an absolute bitch to get off. I had to heat them up and BFH. They were stuck on hard.. I don't have pics of how deep I had to grind to find the cracks. These pics are after I basically ground the weld out to a 90 degree, tube to knuckle then I had to grind in towards the knuckle about 1/4 to 1/2" to get the rest of the weld out..I used a 4.5" grinder.