THESE ARE SLIGHTLY USED ALAN JOHNSON .937 ROLLER LIFTERS I GOT THESE IN A MOTOR THAT I BIUGHT A FEW YEARS AGO THAT WAS FRESH WHEN I BOUGHT IT SO I DON'T KNOW HOW MUCH RUNNING TIME ARE ON THEM THEY SEEM TO BE IN REALLY GOOD CONDITION.I AM NOT USING THEM BECAUSE WE SWITCHED TO JESEL KEYED LIFTERS THESE ALSO COME WITH THE Z BARS.THESE CAME OUT OF 740 CUBIC INCH SHOTGUN HEMI ENGINE.