i've used a chisel, and about a 2 pound hammer and smack the heck out of them it works but is a little work, and dangerous-don't missed the chisel or you'll wish you hadn't. i did it on my 49 3600 removing step brackets
1949 Chevy 3600 Flatbed all orginal 1964 gmc 4000 1973 gmc 6000 2005 chevy duramax 4x4 1994 chevy 1500 Trucks are GM and Tractors are Orange
"I don't measure a man's success by how high he climbs but how high he bounces when he hits bottom." - General George S. Patton