Aftermarket blocks like our Dart Big M have taller/beefier lifter bores/bosses that require 0.300-inch taller solid roller lifters (PN 866-16). The 0.300-inch taller lifters will enable the link bars to clear the lifter boss. If working with a stock Mk IV block, use solid roller lifters (PN 819-16). The new roller lifters were cleaned up then submerged in a 3-pound coffee can full of Comp’s 15W50 Muscle Car and Street Rod oil (PN 1595-12, case of 12 quarts). Also, the reused Comp Ultra Pro Magnum rockers were soaked in another 3-pound coffee can to lube their needle bearings too.