Even out of order. As long as the lifter face is convex, center is higher than the edges, I have had no problem reusing them. The best is putting them on the matching lobe. Just be smart and look carefully at the lifter face and cam lobes. There must be taper on the cam lobes. I have even used them with new cams. It is still a gamble, don't come crying to me if it does not work for you. Use good oil, 30 wt or 20w50 oil with plenty of zinc. I have only done this with MOPAR cams and lifters, don't bother trying this on a Chevy. You will never find a good lifter or cam in a Chevy.