These lifters don't even have 500 miles on them, only a few 1/4 mile passes. Always used Joe Gibbs oil. My 347 is making power all the way to where I feel safe with hydraulic lifters so I am going solid roller. These lifters are about $900 new, this is where I bought them,
Morel SBF HLT Link Bar Hydraulic Roller - FlowTech Induction
Asking $500 shipped.
Morel SBF HLT Link Bar Hydraulic Roller - FlowTech Induction
Asking $500 shipped.