The lifter is not really a lifter, it is a lash adjuster that just holds up one end of the rocker while the valve holds the other end and the cam pushes down on the middle of the rocker, this adjuster has no way of rotating but it is round so it may rotate just from vibrations or something. On my truck I am driving right now I have tried every kind of snake oil imaginable (since it is my truck I feel free to experiment)and they will not be quiet. I replaced an entire set for a customer one time when they started falling out on a routine basis and it still clattered, took longer but they still would fall out ocasionally. I have thought about welding a tab on the upper end of the rocker so it just don't fall off when it bleeds down, seems someone would have come up with a rocker already made that way but I don't know of any. I have seen when they fall out get jammed under the cam, bend valves, crack pistons, break rocker stands... if it is a keeper engine then you need to adress it, I have a 5.7 hemi to put in mine (supposed to be an easy swap) so I am not too worried about it. BTW my engine has no sludge in it at all and only 130,000 miles. Seems if you drive it every day they don't bleed down enough to fall out, just clatter, usually when someone comes in with a bad one they always say it sat for a week then it was running like crap when they started it. There are no 32 valve 4.7s they are all 16 valve, in later years they went to dual spark plugs.