I rebuild them all the time and never had a come back. I don’t know why people think there are only two 4r100 gods, these Transmissions are very simple and it’s all on how much you want to beef it up. It’s like a race motor there no end .Please don't take this the wrong way, in all do respect, it's not rocket science!! It's all about how much money you want to put in to it. Basic rebuild cost me $600 and a full rebuild will run me $1.500 just in parts (not) including the torque converter .And I get $500 just benching them and I go through every part including full tear down of the valve body .Clean inspect making sure every valve is completely free in movement .