The 1958 Service manual specifies .013" - .018" end play. And in bold letters it states, "Note: It is recommended that the end play be held to the high limit rather than the low. The end play will decrease during operation due to heat expansion." It further states that one should have equal thicknesses of shims on both sides of the axle. This is lots of fun. After measuring end play, you get to run around to both sides of the car and even up the shim packs. We set our end play on the D at this range and have had no trouble. Be very sure to use limited slip length axles with limited slip rears and vice versa. Axle lengths are different. Usually no one replaces the axles, but they will replace the rear end. Gloria Moon