gen 5 and 6 was the first years of the pre set lash so less you remove the tower bolts and use the kit from comp or buy a set of older mark 4 big block rockers arms or roller rocker arms then the ARP stud are needed or the older GM 7/16 studs as they have a 7/16 part of rocker stud that screws in to the head then you would need to drill and tap the head to take older rocker stud . for a engine that had much valve work or been deck or longer valve bigger cams and valve spring with more lbs then many like the bigger stud . BUT if your engine is OEM stock then you preload should be the same as stock and will be ok . less machine work as been done bigger cam sunk valve milled heads all valve height needs to be the same as Then your best bet is the adjustable valve train then you need to buy the parts to make it so .this is much like many engines made have pre load set . there 8 push rods shorter are intake... 8Ex longer .. over the years they are not the same over all length.i hope this is clears up some things