There are three situations where you would not need hardened push rods:
(1) when using stock 5.0L style bolt down (pedestal mount) rockers
(2) when using the old Ford style rail rockers (a small part of the rocker hangs down on both sides of the valve tip to keep the rocker aligned with the valve tip)
(3) when using shaft mounted rockers (i.e. Jessel system)
Otherwise, when using stud mounted rockers it is alway necessary to use push rod guide plates and hardened push rods. Like the other's said.... engine building 101
