so i compared 3007 invader/intruder pistons with 3012 intruder pistons from 81 and up....12's have 2 rectangle rings that are both lower on the piston,top locating pin is in center, bottom pin moved to about 2 o'clock,07 top pin 5 o clock, bottom pin dead center.looks like they were trying for more durablity and had to relocate the anti rotation pins when they moved the rings down on the piston