Stock replacement hydraulic tappet set with a tappet with +.003" oversized O.D. to be used as stock replacement for all 53-84 B.T. models. Precision machined direct replacement tappet body complete with premium quality hydraulic units. Repl. 18522-53A (tappet) + 17920-53A (hydraulic unit). Note: For replacement parts see 512884 +.003" o.s. tappet body 512886 hydraulic unit and 512887 tappet roller kit. 53-65 Panhead 66-84 Shovelhead (NU)