Magnum Roller Lifters

[1] Doubt a Chebby rocker will work; the SBM rockers are very short.
[2] A lifter could still have caused this; if it pumped up, the posi lock or the stud may have made contact with the rocker body.
[3] Harland & Sharp rockers will break just like any other rocker if overloaded or faulty [ post #29 ]
[4] Check the underside of the rockers for contact between the stud & rocker slot, at full lift.