How do I remove the factory rivets from the lower ball joint on my 1995 4x4 yukon?

I am trying to replace my ball joints on my 1995 yukon 4x4.I had enough access to drill and hammer the upper ones out but I didn't know if there is a trick to get the lower ones out. I am on jack stands and it is hard to maneuver any power tools. I ground the head off the bottoms of the rivets. I drilled 3/8 holes in each rivet 5/8 inch deep but they aren't budging even with a electric chisel under the head. Any suggestions would be appreciated.